Allow rtp paths with spaces on Windows

Suggested by @ikurcubic
Merge pull request #454 from vaibhavsagar/patch-1

Allow rtp paths with spaces on Windows

Fixes #451
Fixes #453
Clarified comment for non GitHub example in Configure bundles
Bump version to 0.10.1
Merge branch 'master' into next
change function g:shellesc_cd into vundle#installer#shellesc_cd
Limit default rtp rearrangement

Rearranging rtp so that **all** default directories appear first has the
undesired side effect of not allowing plugins to override default syntax
files.

This changeset limits the rearrangement of the rtp to simply making sure
the first directory in the default runtimepath appears first in also in
the runtimepath after Vundle has finished manipulating it.

This should keep the original bugs fixed and should eliminate the
aforementioned undesired side effect.

Fixes #430
Fixes #456
Bump version to 0.10.2
Correct new version in changelog.md
Change reference of `Bundle` to `Plugin` in the docs
Refactor global variables.

1. Turn global variables which are only needed in one file into script local
   variables.
2. Change all global variables that are not part of the public API (mentioned
   in the documentation) into autoload variables.

These steps are intended to reduce the amount of variables in the global
namespace and to give all global variables defined by Vundle.vim a common
prefix.  The variable g:default_git_proto is part of the public API and is
therefor not changed.  This is the only exception.

Changed:
  g:bundle_dir            -> vundle#bundle_dir
  g:bundle_names          -> s:bundle_names
  g:bundles               -> vundle#bundles
  g:updated_bundles       -> vundle#updated_bundles
  g:vundle_changelog      -> s:changelog
  g:vundle_changelog_file -> s:changelog_file
  g:vundle_last_status    -> s:last_status
  g:vundle_lazy_load      -> vundle#lazy_load
  g:vundle_log            -> vundle#log
  g:vundle_log_file       -> s:log_file
  g:vundle_view           -> s:view
Unchanged:
  g:default_git_proto