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)

Note that I wasn't able to use the `pip` thing at all, so I've added the

```
if __name__ == "__main__":
```

trick, so that it can be run on it's own directly. I'll just symlink it into my /usr/bin and it'll work just fine.

Feel free to reject the request, then I'll keep it in my repo and develop independently (maybe with different name).