Added multiple backends support for Customer companies (Cyrille Bol)
Fixed some bugs from previous commit:

  1- Fixed some typos and small errors that prevented the previous commit to actually work.
  2- Since I had copied the CustomerCompany/DB.pm file from the CustomerUser/DB.pm file, I had forgot to remove some reference to CustomerUser related variables. This is now fixed.
  3- I had forgot to implement the search filter in the CustomerCompanyList function. So, the Customer Company list was never filtered. This is now fixed.

Cyrille Bollu
Merge branch 'cyr_dev_1'
Made adaptation requested by Martin Gruner to my patch for adding multiple backends support to CustomerCompany:

  1- Added a Module line to the CustomerCompany default config in Default.pm (+ Added a Name line)
  2- Added fallback in CustomerCompany.pm for people migrating from 3.2 which have this setting not set in their config
  3- Added a dropdown list to the AdminCustomerCompany module to show the writeable sources where Customer companies can be added.

Cyrille Bollu
Merge branch 'master' of http://github.com/belnet-ict/otrs

Conflicts:
	Kernel/System/CustomerCompany.pm
Merge branch 'master' of http://github.com/OTRS/otrs
Added multiple backends support for CustomerCompany, thanks to Cyrille @ belnet-ict!