Use native easy_install_package instead of shell command

Fixes #29
Work around COOK-2171

Tested with apt-1.8.0 and apt-1.8.2
fixes #40 and fixes #41
Merge pull request #42 from DataDog/apt-18-workaround

Work around COOK-2171
Keeping foodcritic happy
Updated README for 0.1.3
Pass use_ec2_instance_id attributes to options for the handler and correct  comments for the default attribute
Ha, use != user
Merge pull request #44 from novu/master

Fix handler use_ec2_instance_id options