Do not shadow submodules

using object that have the same name as submodules as the weird effect
of makeing `import pip.commands.<something> as <anothername>` fail with
a key error. This fixes it by renamin commands as command_dict and fixin
a few imports to accomodate.

Related to #2149
RELEASE notes
update submodules after checkout
Merge pull request #2172 from Carreau/shadow-submodule

Shadow submodule
Revert "RELEASE notes"

This reverts commit 279569a164910f0ae8f202c724808d631e241ceb.
Merge pull request #2181 from dacjames/develop

update submodules after checkout
Fix for latest setuptools
Merge pull request #2182 from dstufft/fix-latest-setuptools

Fix for latest setuptools
Vendor Packaging
Upgrade setuptools
Implement PEP 440
Merge pull request #1894 from dstufft/use-packaging

PEP 440 Version and Specifiers
Change "Downloading/unpacking" to "Collecting"

"Downloading/unpacking" was misleading and confusing, especially when
the package is never found, as nothing was ever downloaded or unpacked
in this case.

The word "collecting" seems general enough to be accurate and it goes
well with the fact that later on pip will say, "Installing collected
packages".

Fixes: GH-376
Don't warn about /simple/ fallback for PyPI

and display a little more info about the index used.
Merge pull request #2186 from msabramo/smarter_about_displaying_message_about_fallback_to_simple

Don't warn about /simple/ fallback for PyPI
Merge pull request #2185 from msabramo/GH-376_change_downloading_unpacking_msg_to_collecting

Change "Downloading/unpacking" to "Collecting"
Make filter regex more inclusive

so that it filters out more "no previously-included..." warnings from
distutils while installing.

Before:

    $ pip install -e ~/dev/git-repos/pip
    Obtaining file:///Users/marca/dev/git-repos/pip
        warning: no previously-included files found matching '.coveragerc'
        warning: no previously-included files found matching '.mailmap'
        warning: no previously-included files found matching '.travis.yml'
        warning: no previously-included files found matching 'pip/_vendor/Makefile'
        warning: no previously-included files found matching 'tox.ini'
        no previously-included directories found matching '.travis'
        no previously-included directories found matching 'docs/_build'
        no previously-included directories found matching 'contrib'
        no previously-included directories found matching 'tasks'
        no previously-included directories found matching 'tests'
    Installing collected packages: pip
      Running setup.py develop for pip
        warning: no previously-included files found matching '.coveragerc'
        warning: no previously-included files found matching '.mailmap'
        warning: no previously-included files found matching '.travis.yml'
        warning: no previously-included files found matching 'pip/_vendor/Makefile'
        warning: no previously-included files found matching 'tox.ini'
        no previously-included directories found matching '.travis'
        no previously-included directories found matching 'docs/_build'
        no previously-included directories found matching 'contrib'
        no previously-included directories found matching 'tasks'
        no previously-included directories found matching 'tests'
    ...

After:

    $ pip install -e ~/dev/git-repos/pip
    Obtaining file:///Users/marca/dev/git-repos/pip
    Installing collected packages: pip
      Running setup.py develop for pip
    ...
Don't say "Unpacking" if installing from directory

Fixes: GH-2187
Merge pull request #2191 from msabramo/filter_out_more_manifest_junk_when_installing

Make filter regex more inclusive
Merge pull request #2188 from msabramo/GH-2187_dont_say_unpacking_for_directory

Don't say "Unpacking" if installing from directory