Short-circuit CDB_TransformToWebmercator when input is already there
Add "make check" rule

The make check rule prepares test database and runs all tests found
to succeed on my personal local deploy. This is a fraction of all
available tests. The list of run tests should grow over time.

In addition to the "check" rule, which does both db preparation and
test run, there's a "check-prepared" rule that assumes a test
database was already prepared and a "prepare-test-db" which only
prepares the database.
Make CDB_UserTables test more stable by ordering multirecord results

Fixes test run with PostgreSQL-9.3
Merge branch 'stable-usertables-test' of github.com:strk/cartodb into release/2.3.3
* Make CDB_UserTables test more stable by ordering multirecord results
Merge branch 'feature/make-check' of github.com:strk/cartodb into release/2.3.3
* Feature/make check
Merge branch 'features/CDB_TransformToWebmercator-improvement' of github.com:strk/cartodb into release/2.3.3
* Features/cdb transform to webmercator improvement