[sailfish-browser] Do not treat initial page load as navigation

Initial page load must only update the url for the active page.
Fix back / forward navigation loading after browser restart
Use TestObject for tst_webview
Add a unit test for back navigation after restart

The commit containing the fix is SHA1 65bff96e
Add a unit test for clearing tabs and history
Merge pull request #108 from rainemak/navigationFixes

Navigation fixes