Enable code signing in preparation of releasing a compiled version of app.

[dempseyatgithub]

Need a way to keep private build settings like team ID private, but easily usable, while still allowing the open source project to compile without those settings or without a team.

[dempseyatgithub]

Created a private git repository that contains private build settings in a well-known location (/usr/local/etc/xcconfig-private). Currently that only only includes the dev team ID build setting.

With that in place and these changes am able to code sign when the private xcconfig file is present and compile with no team for local running when the private xcconfig file is not present.

Closing this issue.