Correct comments for `Base.prototype.option`

* Change `default` to `defaults`
* Remove `banner` as it's never used for `option`.
Merge pull request #519 from alrra/correct-comments

Correct comments for `Base.prototype.option`
Use SVG badge for Travis
Merge pull request #523 from zenorocha/patch-1

Use SVG badge for Travis
bump deps
code style
main.js => index.js
Fix `#determineAppname()` to always find a name
Feature Base#gruntfile expose a gruntfile-editor API

That allow multiple generator from adding configurations to the
gruntfile.js without creating conflicts when writing the file.
Merge pull request #525 from SBoudrias/gruntfile-api

Gruntfile api (Fix #432)
Check for git prior to calling shell.exec
Merge pull request #532 from TheAlphaNerd/master

Check for git prior to calling shell.exec
Add comment for registerValidationFilter entries.
Typo correction in methodIsValid comment
Fix task queue names
Version 0.17.0-pre.3
Changes appendStyles and appendScripts to be a compelete alias to appendFiles

See #536
Merge pull request #537 from oliverh855/patch-1

Changes appendStyles and appendScripts to be a compelete alias to appendFiles
Clarify assert.file API documentation
Allow helpers.mockPrompt to work without arguments

Fix #538, fix #539