Add app description extraction.
New launcher.

- Multiprocessed launcher.
- New command line arguments style.
State & result recording and error handling.

- If the process is stopped and started again than it will start from previous state;
- It's possible to clear the status if needed;
- At the end it will write the results in text files;
- Keyboard interrupt events properly handled.
Added safety checks

- Check for interpreter version;
- Check for modules.
Enhacements on state file management.

- All write operations copies its content into another file before writing;
- When resuming, the Discoverer class try loading the last stable state;
- If everything fails then it will try the last unstable state;
HTTP request now has a header

- The HTTP request now has a Chrome v32 header.
- If -t=free is passed, then only free apps will be discovered.