improved local test-running ability

call generate-version-file before tests, since they'll fall over if the version file isn't present
use /Users/leohemsted/.virtualenvs/api rather than looking for ./venv/ - if there's some other venv already active, then don't try and look for a current venv to activate

scripts/run_tests.sh

@@ -24,7 +24,7 @@ function display_result {
   fi
 }
 
-if [ -d venv ]; then
+if [ -z "$VIRTUAL_ENV" ]; then
   source ./venv/bin/activate
 fi
 pep8 .