Merge pull request #10 from kvark/t-app

New pluggable architecture for the test application
Add a makefile and tweak .travis.yml
util => mem update
Fixed BWT decoding buffer overflow
New FiniteWriter trait implemented for all Writers
Implemented Ari terminator symbol. Added support for Ari into the test application.
Fixed shared.rs spacing, improved Ari tests to include new write_terminator() functions.