Created HOWITWORKS; cleanup of README

Addresses a request from @chrisboulton in GitHub issue #149

Slight grammar cleanup and content update in README.md
Mention of HOWITWORKS.md in README.md, referring those who want to know more that direction
Expanded and slightly cleaner version of a comment made in #149 that prompted this commit/PR
   was placed in HOWITWORKS.md

Signed-off-by: Daniel Hunsaker <danhunsaker@gmail.com>
Replaced BLOCKING env var with SHORT_POLLING
Removed non-PSR-2-compliant tabs from Resque/Worker.php
Updated to use BLPOP by default

* Revised Resque_Worker::work() and Resque_Worker::reserve()
* Made minor formatting changes for PSR-2 compliance
* Marked tests relying on interval 0 to stop a worker as incomplete
* Marked testBlockingListPop as incomplete
Merge pull request #154 from danhunsaker/readme/howitworks

Created HOWITWORKS; cleanup of README
Updated to use BLPOP by default

* Revised Resque_Worker::work() and Resque_Worker::reserve()
* Made minor formatting changes for PSR-2 compliance
* Marked tests relying on interval 0 to stop a worker as incomplete
* Marked testBlockingListPop as incomplete
Added $workOnceThenShutdown param
Merge branch 'blpop-by-default' of https://github.com/zachgarwood/php-resque into blpop-by-default

Conflicts:
	lib/Resque/Worker.php

Conflicts:
	lib/Resque/Worker.php

Conflicts:
	lib/Resque/Worker.php
Merge remote-tracking branch 'upstream/master'
Finalized work

* Rounded $timeout for BLPOPs
* Added error on invalid $interval value
* Added test for invalid $interval
* Addressed work(0) tests
* Revised inline documentation
Updated HOWITWORKS
Merge branch 'blpop-by-default'