[fixed] Navigation to root URL can fail

Navigation to root URL can fail when the URLStore is setup with
location strategy 'hash'. This happens because URLStore.push
verifies the current path. Unfortunately the used currentPath is
not valid for the location strategies *hash* and *history*.

This change changes URLStore.push so that it uses the location
strategy specific current path. This value is already provided
by URLStore.getCurrentPath.
Merge pull request #163 from bripkens/failing-navigation

[fixed] Navigation to root URL can fail