Fixes issue #102

Changing Vundle "Bundle" references to "Plugin"

Add commands to increase and decrease header levels.

Vundle is changing their interface from `Bundle*` to `Plugin*`.
See 
https://github.com/gmarik/Vundle.vim/blob/v0.10.2/doc/vundle.txt#L372-L396 for more information on this.

Make the default mappings 'buffer local'

If mappings aren't defined as 'buffer local', they are defined in other
files too and this causes conflicts with mappings there.

Fix folding bug if folding disabled option is 0

Don't allow spaces before headers in nav mappings.

Breaks too often when you have code blocks with comments that start with #.

It breaks too often when you have code blocks with comments that
start with `#`, and no one uses spaces before headers.

Add preferred style guide to CONTRIBUTING.

The following error occurs with Vim 7.4.260.
E128: Function name must start with a capital or "s:"

Rename function names to `s:Markdown_`.

Fixes #79

Typos in CONTRIBUTING.

Disable automatically inserting bullets when auto-wrapping.

1. Added setlocal formatoptions-=c to disable automatically inserting bullets when auto-wrapping with textwidth.
2. Added indent/mkd.vim to support auto indent in list.

Every non local identifier must start with g:vim_markdown_ from
CONTRIBUTING.md.

Use https://github.com/karlcow/markdown-testsuite for the tests wherever possible.

Conflicts:
	ftplugin/mkd.vim

Add Toc commands.

Fixed typo in README.md

Indented fenced code blocks can now be correctly recognized.

Add vim-addon-manager installation support

Created credits section, remove link to the outdated homepage.

added vundle install to readme, updated pathogen url to github

Added contributing guidelines and started tests as required by them

issue #50 - No spell checking in paragraph text

Fix unletting non-existant b:current_syntax.

Fixed an issue where `unlet b:current_syntax` occurs when recovering from a Session and b:current_syntax has not been set yet.