added fix for edge case in pip.utils.find_command and moved `BadCommand` raise from `VersionControl.cmd` to `find_command`

Fix broken build on windows

Less brittle path handling for URL construction

As discussed in comments on SHA:  f73385ad more work may need to be done.

Harden test against os.sep differences

Use os.path.join so that we don't have UNIX assumptions in test.

Improve unittests to fix build failure

Extracted helper method and mock that for tests to avoid environment pollution.

Correct handling of default pathext case

Fixed bug #266 and corrected some minor coding style problems nearby.

Fixes #233

This adds tests which failed with existing code and then fixed with change.

Ran tests for test_basic in nose on 2.4.4, 2.7.1, 3.2

Ran full suite under 2.7

----------------------------------------------------------------------
Ran 107 tests in 172.398s

Use INITools instead of virtualenv for multiple-search test; virtualenv triggers unrelated bug #260 on Py3 causing the test to fail.

Manually tested:

python pip/runner.py install --no-install django
Downloading/unpacking django
  Downloading Django-1.3.tar.gz (6.5Mb): 2.6Mb downloaded
Operation cancelled by user
Storing complete log in /Users/pnasrat/.pip/pip.log

This reverts commit 6bbd3efc.

Updated script generators to show a nice warning if setuptools/distribute can't be found during execution.

Conflicts:
	docs/installing.txt