Squashing all the individual commits here. Took a few iterations to setup
tests here.
Added Postgres test. Lets see if this passes

Added psycopg2 to Travis

Added tearDown for tests. This needs to clean rows left from previous test

fixed how _con is initialized

Looks like after drop all rows, the MySQL and Postgres keeps the id count incremented from there on

Check what went wrong with MySQL?

The dates stored are in second accuracy. This caused erroneous test condition. Fix here by just pushing the test time by 5 seconds