Make syntastic#util#parseShebang() aware of /usr/bin/env.
New option for SyntasticMake(): env.

Setting environment variables by prefixing commands with 'VARIABLE=value'
doesn't work under csh.  Solution: let Vim set the environment variables.
Merge commit '4c5ff427230823e80a81aee98f0de8137d163aaa'

Conflicts:
	plugin/syntastic.vim