Change failure message when sites data bag fails to load

The current message assumes the reason the sites were not loaded is because there are none. However syntax errors can also cause the data not to load. The error message should be more specific.
Install Drush via git, close #81
Merge branch 'master' of https://github.com/pmgarman/vagrant-lamp into pmgarman-master
Merge branch 'develop'
Forced rake 0.8.7 to be installed in order to work with ruby 1.8.7
Add all but default databags and webroots to gitignore
Remove trailing whitespace from README.md
Fixed Curl Redirection Issue with downloading magento tools by adding -L
Merge branch 'markpfletcher-force_rake_version' into develop
Merge branch 'mattbostock-patch-1' into develop
Merge branch 'papoms-magento-toolbox-curl-fix' into develop
Merge branch 'develop'
Merge pull request #1 from r8/master

Update from the original