Fix Travis CI by running only 3.6 (for now) on Ubuntu "trusty". (#908)
Fix Travis CI by running only 3.6 (for now) on Ubuntu "trusty". (#908)

We can restore the other linux builds when/if llvm.org/apt is back.
cquinn/ponyc,ponylang/ponyc,ponylang/ponyc,Praetonus/ponyc,Perelandric/ponyc,mkfifo/ponyc,jupvfranco/ponyc,jemc/ponyc,jemc/ponyc,Praetonus/ponyc,Praetonus/ponyc,ryanai3/ponyc,CausalityLtd/ponyc,mkfifo/ponyc,dipinhora/ponyc,Theodus/ponyc,mkfifo/ponyc,lukecheeseman/ponyta,cquinn/ponyc,sgebbie/ponyc,jupvfranco/ponyc,Perelandric/ponyc,boemmels/ponyc,sgebbie/ponyc,ryanai3/ponyc,Theodus/ponyc,Perelandric/ponyc,Theodus/ponyc,lukecheeseman/ponyta,sgebbie/ponyc,Theodus/ponyc,kulibali/ponyc,boemmels/ponyc,cquinn/ponyc,boemmels/ponyc,malthe/ponyc,boemmels/ponyc,ponylang/ponyc,dipinhora/ponyc,malthe/ponyc,lukecheeseman/ponyta,malthe/ponyc,kulibali/ponyc,dipinhora/ponyc,mkfifo/ponyc,sgebbie/ponyc,Theodus/ponyc,CausalityLtd/ponyc,Perelandric/ponyc,jemc/ponyc,sgebbie/ponyc,cquinn/ponyc,CausalityLtd/ponyc,jupvfranco/ponyc,jupvfranco/ponyc,Praetonus/ponyc,malthe/ponyc,kulibali/ponyc,mkfifo/ponyc,Perelandric/ponyc,boemmels/ponyc,jupvfranco/ponyc,kulibali/ponyc,ryanai3/ponyc