Prepare for builtime trends integration

Signed-off-by: Michal Čihař <michal@cihar.com>
Move CI token setup to the travis environment

Signed-off-by: Michal Čihař <michal@cihar.com>
Try enabling buildtime-trend

Signed-off-by: Michal Čihař <michal@cihar.com>
Install buildtime-trend requirements

Signed-off-by: Michal Čihař <michal@cihar.com>
Use defined path for build trend

Signed-off-by: Michal Čihař <michal@cihar.com>
Move buildtime to after_success/failure to get build status

Signed-off-by: Michal Čihař <michal@cihar.com>
Document GitHub setup

Signed-off-by: Michal Čihař <michal@cihar.com>
Do not fail on empty subproject

Signed-off-by: Michal Čihař <michal@cihar.com>
Track time for packages installation

Signed-off-by: Michal Čihař <michal@cihar.com>
Merge branch 'master' into bootstrap