Add shell comments support in yardopts file

[SwagDevOps]

Description

Add shell comments support in .yardopts file.

For example you can write a .yardopts like this :

# vim: ft=sh

lib/**/*.rb                                   \
    --no-progress                             \
    --markup-provider 'redcarpet'             \
    --markup 'markdown'                       \
    --charset 'utf-8'                         \
    --protected --private --embed-mixins      \
    --tag type:'type' --hide-tag 'type'       \
    --readme README.md                        \
    --exclude '/\\.#'

# Local Variables:
# mode: sh
# End:

Before modifications, comments are split as arguments, for example in:

yard/lib/yard/cli/yardoc.rb

Line 296 in 84c983d

files.delete_if {|x| x =~ /\A\s*\Z/ } # remove empty ones

They are seen as:

["vim:", "ft=sh", "lib/**/*.rb", "#", "Local", "Variables:", "#", "mode:", "sh", "#", "End:"]

Instead of:

[ "lib/**/*.rb"]

Completed Tasks

• I have read the Contributing Guide.
• The pull request is complete (implemented / written).
• Git commits have been cleaned up (squash WIP / revert commits).
• I wrote tests and ran bundle exec rake locally (if code is attached to PR).

ATM I don't know how to write a test (in this present context). Cuse there is no example IMHO :

grep -FRin 'yardopts(' spec/

[coveralls]

Coverage remained the same at 93.439% when pulling c4b8a61 on SwagDevOps:add-yardopts-comments-support into 84c983d on lsegal:master.