Wizard text improvements

The wizard should be clearer at certain points:

• There's a typo on the provider selection window: s/user/use
• The provider description page has a wrong subtitle: "service provided by bitmask". May be this page should list the services by this provider
• Text in the bootstrap stages is too technical, either have a simpler explanation text or change the descriptions of the stages (which might be more difficult)

(from redmine: created on 2013-03-25, closed on 2013-04-09, blocks #2078 (closed))