Several updates; functionality nearly 100%

* Added FileReader service (wraps browser implementation in a promise)
* Added $parser for `range` type to properly convert its value to a float before it reaches the model
* Improved `file` type directive to properly handle propagation of updates from the model to the control
* Improved psuedo-transclusion process; Angular's transclusion mechanism was interfering with functionality
* Added `legend` type
* Switched to Angular's `isDefined()` method of determining whether to apply an attribute
* Moved away from creating child scope for each form - current scope is used directly instead
  This is mostly for functionality purposes
* Added support for directives previously unnoticed, and improved support for those already implemented
* Updated demo according to changes in the implementation
* Large amount of progress on documentation in README.md

Still need to complete the documentation before tagging the initial release, v0.0.0, but the rest should be ready.

Signed-off-by: Daniel Hunsaker <danhunsaker@gmail.com>