fix update to remove shares where file doesn't exist on postgres

Without patch, breaks with: Failed to upgrade "files_sharing".
Exception="SQLSTATE[22P02]: Invalid text representation: 7 ERROR:
invalid input syntax for integer: "5,179""

See: https://github.com/owncloud/core/issues/5758

removing unnecessary cruft - no parameter is set, none to pass.

https://github.com/owncloud/core/issues/5758

removing subquery, making more readable

See: https://github.com/owncloud/core/pull/6016#issuecomment-29510979

parameters to sql calls should be arrays

https://github.com/owncloud/core/pull/6016

boosting version to ensure fix gets executed

properly escaping the sql select statement

removing extraneous closing paren.
Refactor update script to class and add unit test
Clean up database before setup the database for testing
Added backticks for Oracle in sharing updater unit test
remove invalid shares with one SQL statement