switch quoting so that shell variables can be extended at runtime

Author: mpapis

.travis.yml

@@ -23,9 +23,9 @@ env:
 
 # execute any number of scripts before the test run, custom env's are available as variables
 before_script:
-  - sh -c "if [[ '$DB' == 'pgsql' ]]; then psql -c 'DROP DATABASE IF EXISTS hello_world_test;' -U postgres; fi"
-  - sh -c "if [[ '$DB' == 'pgsql' ]]; then psql -c 'create database hello_world_test;' -U postgres; fi"
-  - sh -c "if [[ '$DB' == 'mysql' ]]; then mysql -e 'create database IF NOT EXISTS hello_world_test;' -uroot; fi"
+  - sh -c 'if [[ "$DB" == "pgsql" ]]; then psql -c "DROP DATABASE IF EXISTS hello_world_test;" -U postgres; fi'
+  - sh -c 'if [[ "$DB" == "pgsql" ]]; then psql -c "create database hello_world_test;" -U postgres; fi'
+  - sh -c 'if [[ "$DB" == "mysql" ]]; then mysql -e "create database IF NOT EXISTS hello_world_test;" -uroot; fi'
 
 # omitting "script:" will default to phpunit
 # use the $DB env variable to determine the phpunit.xml to use