Edited README.md

Corrected invalid PHP. Converted single quotes to double for deeper code
cohesion. Made intro directions more detailed. Rearranged examples, to
mirror API methods list. Removed duplicate example.
Updated README.md Format

Updated titles and example code format.
Updated README.md format

Fixing display problems
Updated README.md format

Fixing README.md display problems
Updated README.md format

Updated Fenced code blocks to Github standard, to try and fix display
issues:
https://help.github.com/articles/github-flavored-markdown#fenced-code-blocks
Updated README.md format

One last edit to titles, notice that the numbering is wrong under the
'How to use:' section, this is a Github problem.
Updated test.php

Updated the test script. Added PHP longtags, fixed invalid currency
pairs, simplified code and added more tests.
Merge pull request #5 from zackurben/master

Updating readability and functionality