Change pymysql requirement to <0.6.2 so that we can use it with Python 2.6

RM5425
Merge pull request #122 from jmeridth/pymysql_requirements

Change pymysql requirement to <0.6.2 so that we can use it with Python 2.6
Fix tests related to upstream changes

Upstream neutron change on database API:

Sync db code from oslo-incubator
Change-Id: I0e1d86878d3eb924b01e04dced0f90b4e57757d8
Merge pull request #124 from asadoughi/fix

Fix tests related to upstream changes