Fixed unknown constant error on Xcode 6b3

Thanks for the nice project!

I was having a small issue however on the latest Xcode 6b3:

    Undefined symbols for architecture x86_64:
      "_NSVariableStatusItemLength", referenced from:
          __TFC25SwiftStatusBarApplication11AppDelegatecfMS0_FT_S0_ in AppDelegate.o
    ld: symbol(s) not found for architecture x86_64


Not sure if this is an Xcode bug or something dumb I'm doing, but NSVariableStatusItemLength is no longer available on the latest build. Putting the constant value here is a quick work-around until this gets fixed, but is definitely not the right long-term fix.

This is more just a note for anyone else who may stumble on this issue—feel free to reject/pull as you see fit.