Merge pull request #164 from eregon/bigint

Improve a couple Bigint-related things
travis-ci.org support
Merge pull request #165 from sjmackenzie/master

travis-ci.org support
Update .travis.yml
swiped @sjrd's Travis config
multiprecision isn't in boost 1.48
Update .travis.yml
Update .travis.yml
Update .travis.yml
Update .travis.yml
Update .travis.yml