lesscpy.compile needs to clean up tmp file(s)

[mjskier]

When you call lescpy.compile(), it leaves /tmp/yacctab.py behind.

This is an issue in a multiuser environment as that file is owned by the first person to call compile().
If a different user tries to run any program that use that function, compile() will fail as it doesn't have permission to write the file:

To reproduce:
Run the simple one liner on you have at the bottom of the READ.md

print(lesscpy.compile(StringIO(u"a { border-width: 2px * 3; }"), minify=True))

then chmod 000 /tmp/yacctab.py
then try to run the lesscpy.compile command again. You will get

WARNING: Couldn't create 'yacctab'. [Errno 13] Permission denied: '/tmp/yacctab.py'