Changes to enable Docker-based CI build.

(Also update INSTALL a bit.)
2 jobs for master in 2 minutes and 19 seconds (queued for 1 second)
Status Name Job ID Coverage
  Test
passed build-ubuntu16 #1032

00:02:10

failed pages #1033

00:00:08

 
Name Stage Failure
failed
pages Test There is an unknown failure, please try again
Removing configure
Removing install/
HEAD is now at 40b594a Changes to enable Docker-based CI build.
Checking out 40b594ab as master...
Skipping Git submodules setup
$ cd doc
$ make
/bin/bash: line 48: make: command not found
ERROR: Job failed: exit code 1