Fix small bug in RMG-tests triggering bash script.

I hate bash.

this was causing these errors:
./trigger-rmg-tests.sh: line 33: [master: command not found
./trigger-rmg-tests.sh: line 45: [master: command not found

A consequence was the Travis job running RMG-tests thought
everything was a dual RMG-Py/RMG-database job.
They still worked because they used the "master" branch for RMG-Py,
but this way is probably better, and is certainly what was intended.

trigger-rmg-tests.sh

@@ -30,7 +30,7 @@ cd $TARGET_DIR
 
 # create a new branch in RMG-tests with the name equal to
 # the branch name of the tested RMG-database branch:
-if ["$RMG_PY_BRANCH" == "master"]
+if [ "$RMG_PY_BRANCH" == "master" ]
 then
   RMGTESTSBRANCH=rmgdb-$BRANCH
 else
@@ -42,7 +42,7 @@ git checkout $RMGTESTSBRANCH
 
 # create an empty commit with the SHA-ID of the
 # tested commit of the RMG-database branch:
-if ["$RMG_PY_BRANCH" == "master"]
+if [ "$RMG_PY_BRANCH" == "master" ]
 then
   git commit --allow-empty -m rmgdb-$REV
 else