Makefile allows faster compile/test cycle (#416)

* WIP: now compiling and linking without errors but does not run!
* Works for BlinkTest.cpp!
* With the Makefile, repeating tests takes 11 seconds instead of 3 min 17 sec. Changes to a test take about 15 seconds and changes to a source file take about 25 seconds to run all the tests.
* Cleanup to match Arduino CI sample.
* Use jgfoster's branch of arduino_ci to assist in testing performance.
* Add FatFileLFN to Makefile.
* Add `FatFilePrint` to Makefile.

Author: jgfoster

Gemfile

@@ -1,5 +1,6 @@
 source 'https://rubygems.org'
-gem 'arduino_ci', github: 'Arduino-CI/arduino_ci', branch: 'master'
+# gem 'arduino_ci', github: 'Arduino-CI/arduino_ci', branch: 'master'
+gem 'arduino_ci', github: 'jgfoster/arduino_ci', branch: 'makefile'
 
 # Following are alternate ways to reference a specific tag or commit
 # This is helpful when a change to arduino_ci breaks the tests