fix definition of "untranslated value"
improve performance by reading all target_f cells in a single operation, treating the pootle store table as any other localization file from now on. This reduces the number of mysql invocations from n*p to p (being n the number of keys and p the number of projects)
make sure we get the value from the array for comparison (not sure if real improvement nor perf penalty)
Merge pull request #17 from dsanz/performance

Performance