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.
Added boolean combinators (IsTrue/IsFalse) and associated DSL per issue #5
Merge pull request #8 from wix/booleans

Added boolean combinators (IsTrue/IsFalse) and associated DSL per issue #5
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.
Fixed #10 (this actually works around a Scala bug, see https://issues.scala-lang.org/browse/SI-8357).
Moved ValidationTransformTests.scala to the correct package
Hackish POC pending discussion on issue #7
Still hackish, but starting to take shape
Switched failures to a violation-set representation (previously was an ordered sequence, which assumes some evaluation order and doesn't deduplicate e.g. null issues).
Proof-of-concept solution to issue #7 (note massive behind-the-scenes API chagnes on the branch).
[#7] Added a type constraint to BaseValidator so it only applies to reference types + cleared up some leftover code
[#7] Introduced NullSafeValidator (adds a null safety layer over BaseValidator) + added a bunch of reference type constraints
Removed extraneous (experimental) API method