Removed hardcoded path to migrations directory from alembic.ini
Removed hardcoded path to migrations directory from alembic.ini

Now for path construction to directory with migrations scripts special
variable %(here)s is used which allows to manually execute alembic
commands from any position in project's source tree.

Change-Id: I5e39a64590ee52975f8909abd299c51315a1b076
Closes-Bug: 1413335

eayunstack/fuel-ostf,eayunstack/fuel-ostf,mcloudv/fuel-ostf,stackforge/fuel-ostf,mcloudv/fuel-ostf,stackforge/fuel-ostf