Added links to learn more about Microsoft Reactive Extension. [ci skip]

Update xctool in `before_install` hook.

Fixed invalid environment variables.

Removed installing xctool.

Updated `.travis.yml` config

Updated Travis config to play well with CocoaPods.

Added Travis CI build status icon to README.

Configure project to integrate with Travis CI.

Removed outdated memory leaks trace file.

New Instruments `.trace` data

Merge remote-tracking branch 'origin/master'

Added Instruments trace data for RAC disposable growth rate.

Refer to workspace instead of project.

Added description on MVVM pattern.

Scaled down image sizes.