get the callers in fctlog

- Add more fctlog calls in testapi - as main entry point for tests
- check backtrace in fctlog for the line number
- print this information in the log file for now, possibly interesting
  in live view once we agree on a way to get it there

t
Merge pull request #132 from os-autoinst/gather_line_number

get the callers in fctlog