Add a PSTN text input in the sidebar
added SPAView for handling dialer display
moved SPA model to shared models module
added method for checking capability support to SPA model
added SPA#dial method
Updated sidebar app to listen for SPA's dial event
sidebar spa-connected event listener to store capabilities
updated styles for the dialing form
less restrictive pattern for pstn number input
hide PSTN dialer when user is not signed in
updated dialer styles
added tests for SPAView#display()
Merge pull request #348 from n1k0/pstn-dialer

Added PSTN dialer in the sidebar