Allow the user to pass in a function to be applied to metric names
as they go though the system. Provide one that ensures valid
metric names
python 3.3 does not have the u syntax. Luckily the test does not require it
using the context manager was cute, but we really should be sure we can construct the connection with sanitation
fix readme
put in a - for every character removed to indicate invalid characters
Seems like yall should support python 3.4
Update contributor section
Release 0.5.0 with ability to sanitize metric names; other minor changes