Add a new task checklicense and fix some bugs in distro_check.py
distro_check.py: Create a new function called create_log_file to reduce a lot of repeat code in distrodata.bbclass.
We needn't to create log file in function save_distro_check_result, because the log file has been generated in check_eventhandler.
Another bug is that we maybe access the /tmp/Meego-1.0 before we create this file.
Add a judge statement to decide whether we need to create this file firstly.
distrodata.bbclass: Add a new task checklicense to collect missing text license information.
This can help package-report system to know how many recipes are missing license text.
