Add role linuxbrew
Install rbenv-gem-rehash through linuxbrew
Remove role node

Instead, use one installed by linuxbrew
Source rbenv init script in .bashrc
Install ruby through rbenv installed by linuxbrew
Remove role anyenv
Fix typo

linexbrew ->
linuxbrew
   ^
Install gem packages only when rbenv is correctly installed
Add linuxbrew path

`path` arguemnt has been added to `homebrew` module in ansible 1.6
Fix currently invalid path in homebrew module

Homebrew module currently consider `$HOME/.linuxbrew/bin` invalid path
because it contains a dot.
Install ruby by git-cloned rbenv

Yet fail in installing ruby 2.1.1 on ubuntu 14.04
Run following command manually to install ruby 2.1.1

```sh
curl -fsSL https://gist.github.com/mislav/a18b9d7f0dc5b9efc162.txt | rbenv install --patch 2.1.1
```
Merge branch 'master' into linuxbrew
Change ubuntu task to ubuntu role
Disable guest session on lightdm
Merge branch 'linuxbrew'