Fix travis error when executing openssl config script
This is probably perl which comes with precise is too old.  Upgrading
travis build to use trusty fixes the issue.
+dist: trusty
language: cpp
compiler:
- clang
- gcc
-sudo: false
+sudo: required
addons:
apt:
sources:
- ubuntu-toolchain-r-test
- - llvm-toolchain-precise-3.8
- - george-edison55-precise-backports
packages:
- g++-5
- clang-3.8
