Reorganize unit-tests and test workflow

+ Moved unit tests out of tests/ and into their respective modules.
+ Rewrite makefile and added these tasks:
  + <MODULE>/<SUBMODULE> -- byte-compile a specific module
  + test:<MODULE>/<SUBMODULE> -- runs tests for a specific module
  + testi -- run tests in an interactive session of Emacs (WIP)
  + run -- opens an Emacs session with this config; useful when it is in
    a non-standard location.

.travis.yml

@@ -5,7 +5,7 @@ before_install:
   - export PATH="/home/travis/.evm/bin:$PATH"
   - evm config path /tmp
   - evm install $EVM_EMACS --use
-  - cp test/init.test.el init.el
+  - cp init.test.el init.el
   - INSECURE=1 YES=1 make install
 env:
   - EVM_EMACS=emacs-25.1-travis