Update specs to introduce multi-backend support

Updated specs to move AMQP implementation into its own class.
Updates specs to specify the backend to be used per subscriber.
Moved amqp implementation into its own class.

Added support to the base class to specify which backend to use
Change interface name from backend to enable_backend
Remove unused duplicates from spec helper
Rename test methods to amqp specific names
Change alias to alias_method
Implement redis backend

Implemented redis backend and specs
Minor fixes and examples
updated README
Bump version to 0.0.2
Move backends out of the base.

Enable loading of backends only when required.
Also, enable loading the backend to use outside
the microservice container
Add publishing support outside services

For communicating with the services, it is now possible
to use the required backend module and directly send and recieve
messages without bothering about the protocol.

	modified:   lib/gilmour/backends/amqp.rb
	modified:   lib/gilmour/backends/backend.rb
	modified:   lib/gilmour/backends/redis.rb
modify redis client to use backend from the gem
Modified server.rb to work with any backend as command line argument.
Added dependencies in the gemspec.
Merge branch 'multi_backend' of https://github.com/vertis-infotech/gilmour into multi_backend
Consolidate publishing methods into one
Change echoclient to use consolidated publish API
Merge branch 'multi_backend' of vertis-github:vertis-infotech/gilmour into multi_backend
Bump to version 0.0.3