A new implementation of the ConcordanceProcessor using Regex.

Regex allows for much cleaner code, because the code of the previous
started to be hard to maintain.
Both ConcordanceProcessors pass the unit tests.
It is possible to select which processor will be used using CL arguments.

If the user runs the program with the -c option,
then CharByChar processor is used, otherwise
we use the default Regex processor.
AbstractConcordanceProcessor#process is a template method.

This way we eliminate some of code repetitions.
The test resource files are automatically detected.

There is no longer a need to list which resource files
should be used as input for the unit tests;
the files from the resources/com/datasift/input/
are used.