Add openrtb plugin that is really a mopub one.

Two body templates for mopub bid request are also added along with
an initial (also poor) README. Some of the configuration of the
openrtb plugin are in the file. The idea is in a future make it
more accesible (maybe in the config file) and not global as they
are now.
Merge pull request #1 from pablin87/mopub-plugin

Add openrtb plugin that is really a mopub one.
Add specific config stuff of plugin being set in the settings file.

Some minor changes for the ParameterPlugin interface to make it
receive a config parameter. This config is get from the settings
file and is specific of each plug in(can have anything).
Also make the openrtb plugin independent of the mopub exchange. The
next step will be to make rubicon from this one.
Aslo add initial Readme file.
Add mopub specific settings for the openrtb plugin under
settings/mopub_config.py
Also click notifications for the openrtb plugin.
Fix: only 2% of the bids generates clicks notifications...
Add eclipse settings to gitignore...
Add module tag_parsing. Also add test for it.

This module let you parse an adm field and put in the ip port of
the click and impression url the values given.
Change rubicon plugin to use tag_parsing module.

Create two new methods to extract the path of the click and
impression url. This methods are use by the rubicon exchange.
Also added some test for those methods.
Fix, remove unecesary replacemente.
Merge branch 'master' of github.com:nemiliani/rtb_exchange_sim
Merge branch 'tag_parse'
Make openrtb plugin to use random auction id instead of an increment.
Send micro usd per impression when sending to adserver.

That is when the use_heh_endpoint is False.(aka: hitting RTBKit
directly).