Removed obsolete separator from .travis.yml
Blacklisted test classes from PHPUnit test suites
Added unit tests for the Exceptions
Added Remoteable and CURL driver for Source_Remote

 * Added Remoteable interface
   - It is used in Source_Remote similar to Cacheable
   - It could be set via the constructor.
   - It could be get or set via the `request_driver` method.
   - When making a request `$this->request_driver()->request()` is used.
 * Added CURL class implementing the Remoteable interface
   - It is the default request driver for Source_Remote.
 * Other improvements like more static:: usage.
100% test coverage and some organization to the tests