Fix translatable strings and cleanup unnecessary strings

1.) Reduces the amount of translatable strings as console/qmlInfo() output
is not translated.

2.) Unused error messages have been removed

3.) Additional translation hints have been added.

Change-Id: I59ef36bd75ab1f6d4878657212884e1251b8a04e
Reviewed-by: Aaron McCarthy <mccarthy.aaron@gmail.com>
Fix unstable PositionInfo test.

The speed reported by the position source can vary due to the system
load and scheduling during the test. Increase the tolerence.

Change-Id: I26c0e6a9c19cfe73f7c1c24b133dbd3cc5abc04e
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>