Dash if f2f

These are the changes that we would like to demo at the Dash-IF meeting.

These issues are resolved by these changes:

-	Manifest download failures do not report errors. (https://github.com/Dash-Industry-Forum/dash.js/issues/88)
-	If attachSource is called with undefined 2 times, it nullrefs. (https://github.com/Dash-Industry-Forum/dash.js/issues/86)
-	Dash should have a proper cleanup process (dispose) (https://github.com/Dash-Industry-Forum/dash.js/issues/85)
-	Remove alerts in code, replace with proper error events bubbled. (https://github.com/Dash-Industry-Forum/dash.js/issues/84)
-	Start in Period results in negative time (https://github.com/Dash-Industry-Forum/dash.js/issues/74)
-	using dash.min/all.js in pages that use Require.js (https://github.com/Dash-Industry-Forum/dash.js/issues/70)
-	Handle non-integer durations correctly (https://github.com/Dash-Industry-Forum/dash.js/issues/66)
-	Multilevel buffer rebased on development (https://github.com/Dash-Industry-Forum/dash.js/pull/52)
-	Use parallel XHP requests to fetch segments (https://github.com/Dash-Industry-Forum/dash.js/issues/42)
-	Issues when segment durations vary (https://github.com/Dash-Industry-Forum/dash.js/issues/39)