Initial refactoring of description framework + introduced ValidatorBase and rewrote quite a few validators to match. This will introduce a whole slew of breaking changes.

All but 2 tests pass, so more work is needed.
Update README.md
Update README.md
Added boolean combinators (IsTrue/IsFalse) and associated DSL per issue #5
Fixed BooleanCombinators for new description framework
Fixed SpringAdapterBase to take into consideration that Violation.description is now optional (tests now pass)
Additional documentation
Merge branch 'master' into descriptions

Conflicts:
	core/src/main/scala/com/wix/accord/combinators/BooleanCombinators.scala
	core/src/test/scala/com/wix/accord/tests/combinators/BooleanCombinatorTests.scala
Merge pull request #9 from wix/descriptions

(BREAKING CHANGE) Complete rewrite of the description framework.