Reorganize development and test dependencies

added simplecov for code coverage, moved dev dependencies to Gemfile
added gitignore
use simplecov when running tests
fix test failure for one_of
rename exclude_spec to match method name
run tests in random order
move test dependency requires to spec_helper
rename one_of_spec to parameter_sets_spec
rearrange dependencies in Gemfile
move test app to spec/
move example to top level directory
fix example
tests for transform and default options
specs for parameter coercion
specs for parameter validation
fix indentation in validate! method
remove tests from TODO in README
Minor reformatting
Bumping version to 0.1.2