[#4] Refactoring to use a map to hold the Elvis's configuration.
Merge remote-tracking branch 'origin/elbrujohalcon.10.macro.names' into jfacorro.4.commit.hook

Conflicts:
	config/app.config
	config/elvis-test.config
	config/elvis.config
	config/test.config
	test/elvis_SUITE.erl
[#4] Integrated changes from @elbrujohalcon and changed files representation to allow providing its contents.
[#4] Added macros for constants like file extensions and file search pattern. Fixed wildcard expression.
[#4] Added tests for git-hook.
[#4] Removed validate function from elvis_config, validation is done through pattern matching in run.
[#4] Removed run/1 and moved its code to rock since rock/1 only called run/1.
[#4] Update README with new command.
[#4] Modified the order of Usage sections in the README.
Merge pull request #33 from inaka/jfacorro.4.commit.hook

[#4] Added git-hook command