Adding exploit for OSVDB 87353

Adding an exploit for OSVDB 87353, which allows for a remote file
inclusion in the Advanced Custom Fields plugin for Wordpress. and shell
given that url include is enabled in the php installation.
Code style fix!

Now variable names are in-line with the coding guidelines!
Fixed the check

Turns out the export returns a 500 by default. Fixing.
Adding a damn space

It suddenly jumped at me that there was a missing space in the module
info. Couldn't unsee.
Adding a PLUGINSPATH option

Adding a PUGINSPATH option as per FireFart's comment.

Because the path to plugins(and wp-content) can be changed, I've added a
PLUGINSPATH options.
This allows for targeting of sites where either folder has been moved,
by specifying the relative path to where all plugins are stored.
Fixing from crlf to lf

By accident the line endings changed to crlf.

Mihi pointed out that the last diff was funky because the commit by
accident had crlf rather than the lf from the initial commits.

Also adding an email, as per the HACKING guide and since hdm pointed out
the usefulness of it.
Multiple change for Juan

Incooperated changes as per Juan's suggestions.

- Removed redundant space option for the payload
- Doing the uri more intelligently
- Detecting allow_url_include being disabled and reporting it
- Moved to unix/webapp
- Removed redundant handler call
- Adding to description that this requires allow_url_include to be
enabled
make msftidy happy
Merge branch 'master' of git://github.com/rapid7/metasploit-framework