llvm31 and llvm32 have been moved to homebrew-boneyard

...and are no longer supported. This repository will maintain formulae
for the three most recent versions of llvm.
llvm3[345]: fix path in caveats
llvm3[345]: bottle against system python
llvm3[345]: use absolute dylib IDs
llvm33: update 3.3_1 bottle.
llvm34: update 3.4.2 bottle.
llvm35: update 3.5.0 bottle.