Deprecate support for Go < 1.5

Some of our dependencies are failing to build on 1.4 nowadays...

Signed-off-by: Stéphane Graber <[email protected]>

Author: stgraber

Diff for: .travis.yml

@@ -4,7 +4,6 @@ os:
   - osx
 
 go:
-  - 1.4
   - 1.5
   - 1.6
   - tip

Diff for: README.md

@@ -32,7 +32,7 @@ can take your [first steps](#first-steps).
 
 We recommend having the latest versions of liblxc (>= 1.1 required) and CRIU
 (>= 1.7 recommended) available for LXD development. Additionally, LXD requires
-Golang 1.4 or later to work. All the right versions dependencies are available
+Golang 1.5 or later to work. All the right versions dependencies are available
 via the LXD PPA:
 
     sudo apt-get install software-properties-common

Diff for: specs/requirements.md

@@ -1,7 +1,7 @@
 # Requirements
 ## Go
 
-LXD requires Go 1.4 or higher.
+LXD requires Go 1.5 or higher.
 Both the golang and gccgo compilers are supported.
 
 ## Kernel requirements