Added support of branch names in the Incoming and Outgoing pages of Pull and Pull wizards.

Was already merged in Bitbucket before import, marked as merged by the import user

Second and last amendment to Peter Kronenberg's feature request: the branch names configured by the user in the first step of the Pull wizard (or the Push wizard) should used in the Incoming page (respectively, Outgoing page).

I write "should" because I have no use case for testing this and setting up such a test would be too cumbersome.

Unlike previous commits on this issue545 branch, this one does not propagate the implemented behavior to bookmarks for the simple reason that hg incoming and hg outgoing have no support for specifying bookmarks, whereas hg pull and hg push support the specifying of both bookmark and branch.