Tests: Update infrastructure & add travis config (#100)

* Tests: Move tests infrastructure, set up travis

Consolidates the composer files so we can run install once in travis.

* Return empty array if no values are $_POST'ed to the form

Fixes an issue with tests + null values in logs

* Clean up some naming & create helper functions for tests

* Debug travis

* Remove debug

* Fix notices on form

* Turn on multisite flag

phpunit-watcher.yml.dist

@@ -0,0 +1,11 @@
+watch:
+  directories:
+    - plugins/wporg-5ftf
+  fileMask: '*.php'
+
+notifications:
+  passingTests: false
+  failingTests: false
+
+phpunit:
+  binaryPath: mu-plugins/vendor/bin/phpunit