go: remove :GoPathClear and use :GoPath "" for reseting the GOPATH

Merge pull request fatih#403 from choplin/fix-neosnippet

fix neosnippet support

Merge pull request fatih#348 from koenwtje/readme-cleanup

Readme cleanup

Merge pull request fatih#321 from andrewstuart/master

Add a few snippets, mostly for testing

Merge pull request fatih#308 from fd0/fix-indent

Use shiftwidth() instead of '&shiftwidth'

snippets: we don't need this extra line