Readme and bitcode fixes

[ryantrem]

Two totally separate small changes in this PR:

1. Fix an incorrect path in the readme, and re-add the flag to disable ARC (I thought this wasn't needed but it turns out it is)
2. Enable bitcode - I tested this out and everything seems to work fine. Compile time seems about the same, compiled libs are about the same size, and bitcode enabled libs can be consumed by projects that either have bitcode on or off, so as far as I can tell there are no downsides to this change.