Initial draft for streaming.
Gems updated/added.

Added YARD and Guard, updated Rspec.
Refactored Client to be thread-safe.

It used to keep the API key in a class variable, which was very thread
unsafe at it's shared across every instance of the Client.

Also, moved errors to their separate file, and Client is now defined in
lib/rmeetup/client, while lib/rmeetup only requires everything.
Updated readme (docs).
Guardfile added.
Moved streaming code to lib/
Documentation to .md
Update README.md
Rake task for running tests added.
Travis config added.
Added myself as a contributor.
Travis config needs to start with a dot.
Some bureocracy (config cleanup).
String#camel_case in one line
Remove support of Ruby 1.8.7
Clean whole gemspec.
New gemspec.
CodeClimate and TravisCI status imgs.
Versioning file fixed.
More config updates.