v0.4.0

Changes between: v0.3.2..v0.4.0
f8ef756 Updated version for 0.4.0 release.
8beda99 Merge pull request #20 from olcf/improve_solver
90f2815 Added support for not operator and updated image hash generation.
93016a2 Added a sleep to the build loop to lower CPU usage.
1e316a8 Fixed Version bug due to conditionals.
1d7c381 Huge performance increse of the build recipe solver.
b0d9f28 Added solver timing.
f901c23 Fixed bug with image hashes.
ad9d796 Total build time.
1095d4a Added a optional-dependencies section for 'docs'. And fixed bug with logging levels.
c4147cb Made failure of image cleanup a non-critical error.
7779d21 Fixed some bugs/added some error handling.
fa84662 Enabled recursive use of variables.
fbd50d6 Gracefully catch keyboard interrupts.
5bec9c0 Lots of reformating and tweaking the opensift backend
4c87264 Enabled logging for Python API
21db118 Update README badge
6e525c5 Test using the workflow run context
6482040 Update build workflow run-name
90c4b2a Updated build workflow trigger
ebbdd9b Trying a \r
bd3a7c8 Updated triggers for build workflow