Edited Formatting

Added code indention, Added function comment blocks, made syntax
cohesive.
Updated function comments.

Updated the function block comments.
Updated ticker / added order_book functions.

Updated ticker function to correctly call the ticker method, added
order_book function to utilize the 'order_book' functionality of the
Cex.io API.
Changed PHP tag, fixed place_order function.

Changed PHP from short open tags to standard open tag. Fixed variables
in the place_order API call.
Updated parameter data types

Updated the data types of parameters in function comments
Updated readme

Changed non-PHP code to PHP code, and formatted. Fixed incorrect
currency pairs throughout document.
Fixed place_order function

Fixed the 'couple' in the api call for the place_order function.
Merge pull request #4 from zackurben/master

Updating readability and functionality