Adding image filter, xslt filter, and geo ip as dynamic modules

[edrw-bt]

Tested builds on the vagrant boxes edrw/centos7-64 and ubuntu/trusty64.

I updated the rpm changelog to include a note about the update. I assumed this would be version 1.13.6.2-2 of the package. Did not update the deb changelog since I saw debuild asks for the key of the user who last edited the changelog so I figure that should be OpenResty Admin.

Encountered an issue with debuild trying to sign the package after building it and blowing up because the secret key was not available. I added the args -uc -us to the debuild command to prevent it from attempting to sign the package. Noticed that currently the package is signed in a separate step that is kept commented out. Would you like me to add that change to the branch or submit a separate PR so deb builds will work for other contributors without having to edit the Makefile?

This is my first time messing with packaging, let me know if you see any issues that need to be addressed.