Fixed #13 -- Added support for running tests using tox.
Merge pull request #14 from sergeykolosov/ticket_13

Fixed #13 -- Added support for running tests using tox.
Introduced a setting to configure 'compress_level' (for pylibmc 1.3.0+).

Allows to set the compression level via the Django setting
`PYLIBMC_COMPRESS_LEVEL`. The setting value is respected only for
pylibmc 1.3.0 and above, otherwise defaults to 1 (Z_BEST_SPEED)
which is hardcoded into the pylibmc itself.