webapp: Rework xmpp nudge to prompt for either xmpp or a ssh remote be set up.

This commit was sponsored by Nathan Howell.
devblog
Merge branch 'master' of ssh://git-annex.branchable.com
update
Merge branch 'master' of ssh://git-annex.branchable.com
Added a comment: I can't add special remotes
removed
Added a comment
Added a comment: I can't add google drive as remote
Merge branch 'master' of ssh://git-annex.branchable.com
Merge branch 'master' of ssh://git-annex.branchable.com
Merge branch 'master' of ssh://git-annex.branchable.com
fix title (#150)
Merge branch 'master' of ssh://git-annex.branchable.com
Remove wget from OSX dmg, due to issues with cert paths that broke git-annex automatic upgrading. Instead, curl is used, unless the OSX system has wget installed, which will then be used.
note automatic upgrade issue
nuke tmp dir so things don't linger between builds
update