Client: Complete rewrite of deltacloud-client

- Now use Faraday HTTP lib
- Superb error reporting (based on Faraday middleware)
- Documentation
- Easy to read/fix bugs/add features
- Compatible with jRuby/MRI 2.0.0
Client: removed doc/* directory
Client: Complete revamp of deltacloud-client unit tests

- Use minitest instead of rspec
- Use VCR by default for tests (rake test_live override this)
- Coverage >90%
Client: Added VCR fixtures for testing
Core: Updated travis to run deltacloud-client tests
Client: Method documentation fixes
Removed 'pry' from client Rakefile