REDIS_BACKEND_DB env variable added

It's enable the possibility of use a different db index on redis backend
Fix composer example
adding support for remote redis instances (such as redistogo) that require authentication
Merge pull request #88 from lboynton/patch-1

Fix composer example
Merge pull request #89 from trimbletodd/master

Adding support for remote redis instances (such as redistogo) that require authentication
Merge pull request #85 from charly22/patch-1

REDIS_BACKEND_DB env variable added
Added a PREFIX environment variable to set the Resque prefix
Merge pull request #97 from ruudk/feature-prefix-env

Added a PREFIX environment variable to set the Resque prefix
Added PCNTL extension check on composer file
Update README.md

updated link to the new resque repo
Merge pull request #103 from matteosister/patch-1

Update README.md
Merge pull request #99 from rajibahmed/master

Check for installed pcntl extension via composer.json
Merge branch 'master' of github.com:chrisboulton/php-resque

Conflicts resolved:
	bin/resque

Signed-off-by: Daniel Hunsaker <danhunsaker@gmail.com>