Fix dependency on puppetlabs/nginx

Sorry about the trouble, but your module will not cleanly install from the Forge without this patch due to a slight difference on the puppetlabs/nginx dependency expression. This patch should fix the problem, once a release including it is made to the Forge.

Prior to this commit, the dependency on puppetlabs/nginx stated
>0.0.1 which means that PMT needs to find a module greater than
0.0.1. Since that's the only version of puppetlabs/nginx available,
PMT will fail to install lboynton/gitlab cleanly.

This commit modifies the expression to say greater-than or equal-to
0.0.1 -- >= 0.0.1. A full list of supported expressions can be found
here: http://docs.puppetlabs.com/puppet/3/reference/modules_publishing.html