[recipes] added emacs-mtgox recipe

Include the following information in the pull request:

Summary: This package shows the last Bitcoin average price based on the MTGox ( mtgox.com ) on the mode-line
Association with the package: Maintainer
Link to the repo: http://github.com/niedbalski/emacs-mtgox

Test via make recipes:

```
 • Building recipe mtgox ...
/usr/bin/timeout -k 60 600 emacs --no-site-file --batch -l package-build.el --eval "(package-build-archive 'mtgox)"

;;; mtgox

Fetcher: github
Source: niedbalski/emacs-mtgox

Updating /home/aktive/src/melpa/working/mtgox/
Saving file /home/aktive/src/melpa/packages/mtgox-20140121.1637.el...
Wrote /home/aktive/src/melpa/packages/mtgox-20140121.1637.el
File: /home/aktive/src/melpa/packages/mtgox-20140121.1637.entry
Built in 0.035s, finished at Wed Jan 22 10:04:32 2014
 ✓ Wrote 4.0K -rw-rw-r-- 1 aktive aktive 2.2K Jan 22 10:04 ./packages/mtgox-20140121.1637.el
4.0K -rw-rw-r-- 1 aktive aktive   86 Jan 22 10:04 ./packages/mtgox-20140121.1637.entry 
 Sleeping for 0 ...
sleep 0
```
Test via package-install-file
```
Checking /home/aktive/.emacs.d/elpa/mtgox-0.1...
Compiling /home/aktive/.emacs.d/elpa/mtgox-0.1/mtgox.el...done
Wrote /home/aktive/.emacs.d/elpa/mtgox-0.1/mtgox.elc
Checking /home/aktive/.emacs.d/elpa/mtgox-0.1...
Done (Total of 2 files compiled, 1 skipped)
```