Release v0.3.1(DraftDayPick)

This PR features a whole lot of new features, numerous fixes and contributions.

• added auto-renaming of name/path clashing files. This was a much needed feature due to the numerous issues and questions that users submitted to drive. It was implemented by @kadamski in PR
  #418. You can pass in the '--fix-conflicts' flag or checkout the README for more information.
• help: shorten lines to fix them to 80 char width: This issue was reported offline by @indragiek in #247. It was addressed by PRs #263 and #419.
• fixed non-canonical path imports: This issue was reported by @pefoley2 in issue #398, advocated for and then addressed also by @pefoley2 in PR #397.
• fixed retry errors always being printed on encountering during retry. This issue was reported in issue #407 and addressed by PR #408.
• added pull to a depth: This feature was requested in issue #409 and addressed in PR #411. This now allows you to pull to a certain depth instead of always pulling deeply nested folders until the root, say we have big files in level 3 of massiveFiles, we can pull only until depth 2

$ drive pull --depth 2 massiveFiles content

• fixed pull matches erroneously putting matches in root instead of relative to the current working directory: this issue was reported by @ikwyl6 in issue #389. It was fixed in PR #430.
• added push to a depth: This feature was requested in issue #410 and then added in PR #411.
• stat now returns "Description" field of a file: This issue was reported by @marcoblancas in issue #412. It was addressed by PR #413.
• added editing of description of file: This feature was requested by @marcoblancas in issue
  #414. It was addressed by PR #423. Now you can run

$ drive edit-desc --description "October was here" 2015/10 Photos/October
$ cat description.txt | drive edit-desc --piped 2015/Photos/Winter

• a nice one liner use case for --piped: This was provided by @aerth in PR #425. Basically it involves making a tar of the working directory on the fly without taking up extra disk space and then pushing it up.

$ tar czf - . | drive push -piped backup-$(date +"%m-%d-%Y-"%T"").tar.gz

The power of UNIX filters and pipes. You could even take this a step further and do something else with pipes e.g encrypt your data, let your imagination go free. Please see @l3iggs examples on the wiki here https://github.com/odeke-em/drive/wiki/%5BUse-Case%5D-Backup-a-btrfs-subvolume-to-your-Google-Drive and https://github.com/odeke-em/drive/wiki/%5BUse-Case%5D-Restore-a-btrfs-subvolume-backup-from-your-Google-Drive.

• fixed up depth traversal for mounted push. This issue was reported in #415 and addressed by PR #416.
• fixed up version print output. This issue was reported in #419 and addressed by PR #422.
• fixed up aliases' usage with help. This issue was reported in #421 and addressed by PR #422. Previously 'drive help cp mv ls' retuned the response for an invalid command.
• fixed up stat depth: This issue was reported in #424 and then addressed by PR #426.

This release has had a whole lot of improvements and contributions plus growth. Lots of users are getting familiar with drive, and users are finding new cool ways to make things work for them which to me is a great sign of familiarity and usage of drive, and hopefully easy of use. On boarding of new users has been a lot easier at least from the feedback they have given back in issues.

I would like to thank everyone for the contributions(in the form of code, issues, patience, spreading the word, support etc) but also to the users for using drive. I think we've gained quite a bit of traction and we've learnt a lot.

I'd like to dedicate this release to my newly born little nephew Emmanuel -- if you ever read this in the future: Emmanuel was here and this October 2015 release was lit! Also I'd like to wish Burcu aka @rakyll a happy belated birthday(few hours behind).

Thanks again and enjoy drive v0.3.1