Allow client to set boltdb timeout

[aboch]

• also in case of no persistent connection
• Also fixing CI by bumping go version in .travis.yml

Related to https://github.com/docker/docker/issues/26251 Related to https://github.com/docker/libnetwork/issues/1374 Supersedes #135

Signed-off-by: Alessandro Boch aboch@docker.com

[sanimej]

LGTM