Complete rewrite & improved functionality

Hey, you may remember me from Google+, the only one to react to your post :P

I've decided to completely rewrite the code, so it can be better maintained - now using class, cleaner formatting, it's divided into smaller functions etc.

**Improvements:**
- Now using to `python 3`
- You can specify working directory without `cd`-ing into it (use the `--workdir` or  `-d` argument)
- Supports more script types:
  - '.py'
  - '.rb'
  - '.pl'
  - '.sh'
  - '.php'
  - '.jar' (uses `java -jar` to run it)
- Can **run anything executable** (eg. set by `chmod +x filename`)
- Can **run shell commands** (eg. `cat error.log`, `rm -rf`, `ls --all` ...) in the specified directory
- Asks for confirmation before deleting all shortcuts
- Database file is stored in `~/.jumprun/data.sqlite` - so that when more files need to be added, they can all be in the same directory (instead of polluting user's home directory)

Feel free to reject the request, then I'll keep it in my repo and develop independently (maybe with different name).