Update hold.pp

fix for default debian installations

all files in /etc/apt/preferences without _ will be silently ignore according to debian manpage. Addionally its not a good idea to write versionnumber in filename cause there is no way to delete this files if you increase versionumber

Update source_spec.rb

add a way to include debsrc only (useful for debian/ubuntu build server ... jenkins ect)

Update source_spec.rb

var rename

Update source.list.erb

add include_deb "switch"

Update source.pp

"include_deb" defaultvalue = true

Update hold_spec.rb

change the name of the preferences file (hold)

Update source_spec.rb

Update README.md

Doku: 'include_deb' included next to 'include_src' in examples

Update README.md

typo