Switch testing to another Travis-CI & reimplement using browserify-transform-tools

Some stuff I did:
  - switched to Travis-CI for testing. Testling for open-source repos is currently broken. Instead I'm running tests on phantomjs and firefox using tape-run on Travis
  - reimplemented the base functionality using browserify-transform-tools. This removes the need to do some stuff manually (checking filetype, redirect streams, buffer contents, looking for config, ...) and thereby reduces the change of errors.
  - added source-map generation