Install form source typo

Corrected "rm restful.zips" typo in install from source section
Update Hold.php

comments edit
Move error classes to seperate files for better 3rd party PSR-0 compability
Update README.md to reflect pinned httpful version
Merge pull request #70 from pmanning11/patch-1

Update Hold.php
Merge pull request #72 from leonsmith/issue-65

Autoloader file structure improvement
bump version to 0.7.5.0
Merge pull request #69 from leonsmith/patch-1

Install form source typo
Update LICENSE
Merge pull request #75 from timnguyen/patch-1

Update LICENSE