Added top level .Hugo variable with version, commit and generator information
Added Version, CommitHash and BuildDate to hugolib/hugo.go and used it in build
Removed commitHash and buildDate from commands/version.go and used hugolib vars
Merge pull request #694 from derekperkins/hugo-generator

First pass at adding top level .Hugo variable

* derekperkins/hugo-generator:
  Added top level .Hugo variable with version, commit and generator information Added Version, CommitHash and BuildDate to hugolib/hugo.go and used it in build Removed commitHash and buildDate from commands/version.go and used hugolib vars
Fix version date parsing.