Remove rbenv.bash.

I no longer use rbenv.
Add development alias for bundle.
Add cabal path to PATH.

For Haskell packages.
Add 'filetype indent plugin on' to '.vimrc'.
Ignore '.gem' globally.

This is used by `chgems` as a local gem directory.
Set default push configuration to 'simple'.

This matches the Git 2.0 default.