Added service generator for plop, code and unit test examples

[thematho]

Change log:

• Refactor plop templates folders and config to be more flexible.
• Added sinon to npm dependencies (spy, mock and stub library).
• Service Generator:
  • Added Service Template with $http calls and test.
  • Added Services folder and module declaration to group common services.
  • Added Service code example.
  • Added Component using a the Service which uses $http code example.
  • Added Unit Test, mocks and stubs examples for handling service injection and $httpbackend.

Update 1

• Added Filter generator with Unit Tests
  • Added Filter module and Filter example

Update 2

• Added Factory Generator
• Refactor plop configuration

Update 3

• Added Directive Generator

TODO:

• ~~Update README.md file~~
• ~~Filters generator~~
• ~~Factory generator~~
• ~~Directive generator~~

[cooervo]

Why wasn't this merged??

[fesor]

@cooervo I hope i will find some time before weekend to review and merge this PR.

@thematho looks good so far.