Fix wget/win32 codepath for script searching.

The codepath does not appear to have been tested; mv on Win32 is move,
and substitute has 4 arguments instead of 3.

Vundle can manage Vundle, when it cloned as git submodule

When vundle installed as git submodule, git create file '.git' instead of
directory '.git'.

And vundle cannot update by self :(

Changelog does not work on Windows

- add /d switch to cd command to perform drive change
- enclose joined commands with quotes

Instead checking for specific text in the output of the git commands, determine
the status of the bundle by comparing the sha of HEAD before and after the
git pull command.

- as before Helptags returned 'updated'

- addresses #162 issues

Create Changelog when performing BundleInstall!

If no errors exist, the status-line will inform users how to view the
Changelog after BundleUpdate! is completed.

Instead of creating a vundle_update tag to compare changes between update
and HEAD we now use the output from `git pull` to get initial/updated shas.

Distinction between `new` and `updated` simplifies the process
of adding a bundle to the updated_bundle list.

If the Bundle is hosted on GitHub include link to compare the commit range
visually on GitHub.

Keeps track of the current commit with a vundle_update tag before
perfoming an update and adds all commits pulled in the update to a
Changelog accessible via pressing 'u' after BundleInstall! completes.

Link to vimified conf in README

Thanks!

- closes #141

- also work in batches

- having it as a function makes it slower