use travis-ci
do not use operator ""s because of libstdc++
use boost-1.55
show clang version
rehash
use clang as default compiler
force to use /usr/bin/clang++

it seems that /usr/local/bin/clang++ is used
tweak $CC and $CXX
fix path to clang binary
Merge branch 'travis'

Conflicts:
	.travis.yml
build status