[minor] rename action counters for clarity
[doc] entity-relationship in postgresql
[doc] adding some indexes per cyborgshadow's recommendation
[minor] remove `positiveresult` api search, we will do something better later
[minor] increase number of maxproc on API
[medium] API uses absolute path to resources, makes links clickables in browser
[major] migration to postgres, bye bye mongodb

This commit is a giant refactoring of the data model of MIG. Moving from
mongo to postgres introduced a number of constraints in order to fit action,
commands, agents and investigators into a relational database. The result is
a much cleaner, much easier to query, database backend that will let us
create reports much more easily.

Plus, postgresql json support is awesome!
[minor] generator cleanup
[major] postgres migration, take 2
[medium] Fix action and command API endpoints
[medium] API dashboard to display the last 10 actions
Merge pull request #13 from mozilla/postgres

Migrate from MongoDB to Postgresql