[TIMOB-3370][TIMOB-9593] webview fixes

iOS fixes:
Load will fire only for unique urls
Test case is in [TIMOB-3370](https://jira.appcelerator.org/browse/TIMOB-3370)

Android Fixes:
refactor of reload method to properly fix TIMOB-9593 and do setHtml with baseURL pointing to resources dir.
setData now checks for type file and loads from there to get correct baseUrl for relative paths in files
changeProxyUrl now does not fire property change for url.

Note that setting HTML still sets the wrong URL in history and so goBack() will always fail once you navigate away from page(existing behavior)

Test case attached to [TIMOB-9593](https://jira.appcelerator.org/browse/TIMOB-9593)
Regress against KS Webview