Add `ignore_collections` configuration parameter to mongodb collector

New parameter ignores all temporary MapReduce collections created by
mongodb.

Also added a unit test for my previous patch (#254).
First checking of Zookeeper module based on memcached module. Tested and working
Add Shmem to default keys for MemoryCollector
setting default min and max uid values
Merge pull request #306 from knyar/mongodb_ignore_collections

Add `ignore_collections` configuration parameter to mongodb collector
Merge pull request #308 from lrsmith/zookeeper

First checking of Zookeeper module based on memcached module. Tested and...
Merge pull request #310 from disqus/shmem

Add Shmem to default keys for MemoryCollector
Merge pull request #311 from CBarraford/master

set default min_uid/max_uid
PEP8