Warn if the shell is not supported
Warn if the shell is not supported

If the shell is not recognised as a supported ("bash" and "zsh" for now)
then a warning will be displayed in red.

For example on Mac OS X the shell process is named "-bash" (note the
first character) and is not yet recognised as a valid shell name.

enrdstrm/liquidprompt,tkuminecz/liquidprompt,joshuarubin/dotfiles,smadhueagle/liquidprompt,pkkolos/liquidprompt,jonathanjsimon/liquidprompt,joshuarubin/dotfiles,kenrachynski/liquidprompt,colinlieberman/liquidprompt,jaesivsm/liquidprompt,tstone2077/liquidprompt,joshuarubin/dotfiles,tocomo/liquidprompt,milouse/liquidprompt,timhyson/liquidprompt,joshuarubin/dotfiles,dtschan/liquidprompt,mathieumd/liquidprompt,BobHood/liquidprompt,nojhan/liquidprompt,alexprengere/liquidprompt,illwieckz/liquidprompt,lyoshenka/liquidprompt,elementalvoid/liquidprompt,dpilone/liquidprompt,laurentbardin/liquidprompt,tsbarnes/liquidprompt,dan-cleinmark/liquidprompt