Accommodate latest RSpec 3 changes

Avoid passing symbol to describe (fixes #12, fixes #14) and access execution results in tests
using methods rather than hash accessor (fixes #15).
Get 2-99-maintenance branch build working

Previous gemfile change didn't work in 2-99-maintenance where rspec-support is not present.
Also fixes #15 (again) so that it works in 2-99-maintenance as well as RSpec 3, albeit
with RSpec 3 deprecation.
Avoid changing implicit subject altogether and eliminate deprecation warning

Improves #12 and #15 based on Myron's feedback.
Prepare for 1.0.1 release
Avoid use of to_h due to lack of support in older rubies

Third attempt to deal with #15.
Updated readme to include require syntax
Merge pull request #16 from abrahamsangha/readme-update

Updated readme to include require syntax
add homepage URL to gemspec
Update .travis.yml to be in line with rspec-core

Allows rbx failure, amongst other changes.
Add allowed_failure builds to build list
Update .travis.yml to correctly allow rbx failure
Merge pull request #17 from ktdreyer/gemspec-url

add homepage URL to gemspec
Deprecate `should` and `should_not`