Revert "Avoid errors if plugin directory doesn't exist"

This reverts commit 72ce2699b49453e2c1ebcc31efc4cc865b4b6075.
Revert "Add plugins loading code based on PingApp"

This reverts commit dfe97c1bee050c4af2a5a758ab1ad54d340531d7.
Merge branch 'master' of git://github.com/ushahidi/Lamu