Fix bug in helpers.mockPrompt()

Inquirer API allow a single prompt item to be passed as parameter.
`mockPrompt` must also work with this signature.
Merge pull request #485 from SBoudrias/composeWith

Initial take at Base#composeWith()
Update deps and use gulp-coveralls plugin
Implement the RunContext test helper class
Merge pull request #506 from SBoudrias/testHelpers

Add RunContext test helpers (Fix #498)
Don't run install by default in Generator#run()
Release version 0.17.0-pre.1
add assert.notImplement method and improve errors

Now the message is clearer as to which methods cause the test to throw
fix naming conflicts between run queues and methods
fix composed generator not running when composed after base generator is runned
release 0.17.0-pre.2
First implementation
Fixes some API hard time with AST-query
Add inline documentation
Make the Gruntfile API with latest rewrite of AST-Query