refresh travis setup

- indicate that we're keen on caching
- lets not install non-essential gems
- test against a larger variety of ruby interpreters however, lets allow some failures
- enable speedy greens (http://blog.travis-ci.com/2013-11-27-fast-finishing-builds)
refresh Rakefile

- replace Gem::PackageTask with Bundler::GemHelper in
- add description to Rspec Rake task as well as add a common alias for test to simply run spec
refresh .gemspec

- ensure .gemspec is using latest Gem::Specification behaviour
- make sure that test gems are not a 'add_development_dependency'
use new Rake tasks
err on the safer side and use bundle exec instead of assuming --binstub'd installed gems
temporarily ensure test dependencies are installed #88 should fix this
Alias #to_xml to #text
constrain to 1.8.7 compatible version of Rake

- http://docs.seattlerb.org/rake/History_rdoc.html#label-10.1.2+/+2014-03-24
constrain to 1.8.7 compatible version of Rake

- http://docs.seattlerb.org/rake/History_rdoc.html#label-10.1.2+/+2014-03-24
Use lower camel case for TwiML verb arguments

The existing example will not camel case the existing finish_on_key argument to return finishOnKey as expected.
Pins JWT to ~> 1.0.0 and fixes tests.

JWT started to return both the payload and a header when decoding a token since
[this pull request](https://github.com/progrium/ruby-jwt/pull/35). This has
since become part of the version 1.0 release, so this gem might as well
encourage usage of 1.0 and get fixed tests for that.
Merge pull request #86 from karlfreeman/travis-refresh

Refresh Travis setup
Merge pull request #97 from philnash/jwt-test-failures

Pin JWT to ~> 1.0.0 and fix tests
Merge pull request #94 from jfranz/patch-1

Use lower camel case for TwiML verb arguments
Merge pull request #90 from LeoAdamek/alias-to_xml-to-text

Alias #to_xml to #text for TwiML Response
Merge pull request #88 from karlfreeman/rake-gem-refresh

Refresh Rake gem and use new tasks

Conflicts:
	Gemfile
	twilio-ruby.gemspec