Fix predicate invocation in test case
Move requirement to the right place
Update test cases for Ruby, Rust and Less
Work around #531 and Emacs bug 19206

CC Mode manages to track the wrong source file during installation of D
Mode via Cask, which later breaks when D Mode is enabled, because CC
Mode then tries to load a wrong source file which isn't in `load-path'.

See http://debbugs.gnu.org/cgi/bugreport.cgi?bug=19206
Be more graceful

Sleeping never matches exact times, so be a bit less strict.
Improve error message on invalid selectors