Bundle configuration options that are inferred from the bundle specs
overwrite user provided ones. This used to prevent users from changing
the name of directory where the cloned bundle should go, for instance.

Keep the user provided options with a preference over inferred ones.

Warn the user when a leading or trailing space is found in one the
bundle specs they have configured using the Bundle command.

- causes #203

This reverts commit 1e140c9f6b.

- make it append only (instead both append + prepend)
- which draws *_rm_a and *_add_a useless as &rtp order gets preserved
- benefits: simpler, faster, less code

- also work in batches

- having it as a function makes it slower

- as `http` one just redirects to `https` on GitHub

- use `let g:vundle_default_git_proto = 'git'` to set default protocol
to build URIs to clone from

- "transcient bundle" - a bundle installed with :BundleInstall or interactively
  without being declared in .vimrc

- treat them the as if they were configured
- so everything works the same

- ie before this change helptags weren't generated automatically
  with `BundleInstall bundle` or with interactive mode

- it changes the way `:BundleClean` works, since it removes directories
  that aren't bundles
- FIX: `:source .vimrc` to let `:BundleClean` remove transcient bundles

- closes #99

- closes #110

Uris for repos specified as user/repo end up being https://github.com/user/repo. For some reason, github allows cloning from such uris, however, it is better to rely on the addresses that github provide for cloning, and those include the trailing .git

This change appends .git to github repo uris when needed.

- otherwise it defautls to vim-scripts repos
- closes #69
- TODO: pass options aswell

- closes #37
- join is useless there

GitHub usernames cannot start with an underscore, but they can be a
single character long.

- ie, like this
Bundle 'gmarik/vundle'

- this was intended for case when user uncomments installed `Bundle` and
reloads .vimrc; which should make the bundle available
- TODO: later

- fixes https://github.com/gmarik/vundle/issues#issue/3
- TODO: not the most efficient approach

- so it's ready to use right after installation

- vundle.vim - entrypoing and loader
- config.vim - configuration and runtimepath management
- installer.vim - installation and docs