Merge pull request #10 from owncloud/force_sortindex_int

Cast sortindex to int
Cast numRows() to int before comparing identity

For some configurations, numRows() returns a string instead of an int.
Casting it to int before comparing using === or !== removes this issue.

See commit 952414dba7bc8ca and issue #11.
Merge pull request #12 from owncloud/numrows_cast_int

Cast numRows() to int before comparing identity
Add install/uninstall info

Add information about installing and uninstalling Mozilla Sync.

Closes issue #13.
Uninstall info: Made SQL statements more generic
Remove sortindex and modified if they are null

Dont' send null values for sortindex and modified if they are not set in
the database. Instead remove them from the resulting array.

See issue #7