Adds tito-ized RPM build scripting

This pull request adds support for using Tito to build memkeys as an RPM, tied to the Git SHA corresponding to the current release (0.1).  More information on Tito may be found here:

https://github.com/dgoodwin/tito

A memkeys SRPM built according to the last release Git tag may be performed using the following command:

# tito build srpm

SRPMs may be built from git HEAD using the following syntax:

# tito build --test srpm

When a new release is to be minted, a new RPM release may be added by making the requisite version changes to the specfile then running a:

# tito tag
# git push && git push --tags

With these tools, it is my belief that we can soon submit memkeys to the Fedora project for widespread adoption.  Let me know what you think, and thanks for the consideration!