Closes #496
Added basic tests on migrationvalidator, were missing
Merge pull request #499 of tommarien\FB-496

* Fixes expression validation to throw if migration contains same
* expression twice
  Closes #496 Added basic tests on migrationvalidator, were missing
Revert "Merge pull request #482 of daniellee/integration_tests_cleanup"

* Had to revert pull because locking on sqlserver sequence tests
This reverts commit 5e706419c7ae57e68f751454ded1c5be91d1a7ea, reversing
changes made to adf54bb83669d2609c2b6e942b846313ee560fb2.
Bump version for release