Dev Cordova tasks

#### Some Tasks That Will Be Helpful for Developing Cordova Apps
- Added a `sass` task: watched, compiles and minifies the css
- Added a `connectWatch` task which starts a connect server, watches for changes to html & js files and re-loads browser
- Added a `dev-cordova` task to the gulpfile which demonstrates the new tasks
- Also added some test html, js and sass files that are used by `dev-cordova`
- Updated `README.md`