.vimrc - add various config and use Vundle as package manager

Signed-off-by: Pang Yan Han <pangyanhan@gmail.com>
Rename dotfiles to remove dot prefix

This is due to a change in how this repository will operate.
Instead of using the `$HOME` folder as the git repository and tracking the
dotfiles right there, we will be using the `$HOME/dotfiles` directory to
house this repository. The actual dotfiles in the `$HOME` folder will
source / import those tracked in this repository.

More detailed setup instructions are available in a newly added
`README.md` file.

Signed-off-by: Pang Yan Han <pangyanhan@gmail.com>