Catch itegrity errors and return 400.

When creating or updating an organisation an itegrity error is raise if the name is already used.
This change adds a new error handler for the organisation to catch the named unique index and return a 400 with a sensible message.
We have an other error handler for unique service names which was caught in the error handler for all blueprints. A new error handler for the service_blueprint has been created for catch those specific unique constraints.
This is a nice way to encapulate the specific errors for a specific blueprint.

.gitignore

@@ -72,3 +72,5 @@ celerybeat-schedule
 
 # CloudFoundry
 .cf
+
+/scripts/run_my_tests.sh