Display installed versions

This is based off https://github.com/pypa/pip/pull/2206 (because without that, this code barfs on wheels)

Display versions installed after install

Name and version are displayed in a `pip freeze` like format, sorted by name. This makes it much easier for the user to ascertain what the `pip install` actually did.

##### Before:

    Successfully installed pyramid zope.interface translationstring PasteDeploy WebOb repoze.lru zope.deprecation venusian

##### After:

    Successfully installed:
    PasteDeploy==1.5.2
    WebOb==1.4
    pyramid==1.5.2
    repoze.lru==0.6
    translationstring==1.3
    venusian==1.0
    zope.deprecation==4.1.1
    zope.interface==4.1.1