Allow to keep the build dir after succesful build

Set the option cleanupbuild to False to keep the build dir after a
succesful build. Can be helpfull for debugging purposes.
only warn about mismatch between provided build specs and available specs for easyconfig format v1.0
fix collaboration between --robot and --try-X
replace faulty use of tweak with tweak_one
extra check for finalpath being available
Revert "only warn about mismatch between provided build specs and available specs for easyconfig format v1.0"

This reverts commit ab9cd62f2eb4327af195a141ec2403b65adb762e.
only trickle down build specs when required/correct
Merge branch 'develop' into robot_try
enable --robot with default paths when --try-X or --dep-graph is being used
add unit test for recursive --try
fix new unit test
Merge pull request #931 from JensTimmerman/finalpath

extra check for finalpath being available
fix remark
Merge pull request #922 from boegel/robot_try

fix collaboration between --robot and --try-X
Merge branch 'develop' into cleanupbuild

Conflicts:
	easybuild/framework/easyconfig/default.py
Merge pull request #11 from boegel/cleanupbuild

sync with develop
fix conflict resolution fail
replace 'cleanupbuild' easyconfig parameter by '--cleanup-builddir' command line option, and enhance unit tests
Merge pull request #12 from boegel/cleanupbuild

replace 'cleanupbuild' easyconfig parameter by '--cleanup-builddir' command line option, and enhance unit tests
Cleanupbuilddir: make help message correcter