wikia.common.perfmonitoring: initial import

@jnrbsn / @michalroszka / @jcellary / @jogura 

https://wikia-inc.atlassian.net/browse/PLATFORM-417
Would it be more pythonic if we used the `@property` for this and the `is_dev()` method? https://docs.python.org/2/library/functions.html#property