Added 3 functions

# fabtools/deb.py
My current directory tree:
```
fabric-scripts
├── fabfile (my fabric scripts)
├── fabtools (awesome fabtools)
├── packages (local copy of *.deb-file for installation)
```
*Example:*
fabtools.deb.install_file('packages/skype_latest.deb') - install file from local 'packages/skype_latest.deb' to remote computer:
* Upload file to remote /tmp/skype_latest.deb directory
* Install file with dpkg -i /tmp/skype_latest.deb
* Delete /tmp/skype_latest.deb

# fabtools/required/deb.py
*Example:*
require.deb.file('packages/skype_latest.deb') - if package 'skype' not installed call fabtools.deb.install_file

# fabtools/utils.py
*Example:*
fabtools.utils.kill_proc('skype') - if process 'skype is running, kill them.