Fix bug with removing flag after "-c"

-c does not take an argument. Why did I think it did?
initial general completer
style fixes
Properly respect ShouldUseNow methods
Remove caching and use Queue.Queue for results

Identifier completer doesn't work good with caching, because it provides
already sorted completions.
fix merge issues
initial ultisnips completer
initial filename completer

Heavy WIP. Currently it uses ctrlp-cmatcher C engine for matching.
Need rewrite
add import exception handling
refactoring
fix listdir behavior; optimizations
remove unused threading stuff
add caching
use list comprehension
remove unused method
remove threading
add proper filepath pattern
respect ~ in paths
respect . and ..
some refactoring