Various vim fixes

If the user has python enabled it will use python to complete, I did some quick comparisons and found it 10-15x faster than the vimscript version(~0.3s to complete with vimscript vs ~0.02s for python on my weak netbook).

Added a dictionary for type abbreviations after I realized racer has multiple types that start with similar letters, but I'm unsure if there's some sort of 'standard' so I kind of copied [DCD](https://github.com/Hackerpilot/DCD).
Also added automatic parentheses insertion for functions.

Attempted to merge function signature with function name but found a bug, reported as issue #38. When that's fixed I'll do that.
![screenshot - 08092014 - 09 30 03 pm](https://cloud.githubusercontent.com/assets/7722833/3868249/ec871a5c-202d-11e4-9171-07e63f92fd02.png)