Create s2i-scala-container for Scala 2.12

[toxicafunk]

The main thing is using a newish SBT version, I chose sbt 1.2.1 but other versions may also work.

Also I encounter a weird issue where parse_sbt_key() from the assemble script did not worked on the new container so I had to hardcode the version to 1.2.1.

[todo]

proxy repo and mirror settings?

s2i-scala-container/2.12.10/s2i/bin/assemble

Lines 49 to 54 in b38a46a

	# TODO: proxy repo and mirror settings?
	function setup_sbt() {
	:
	}
	# crude utility to parse key setting output from sbt

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This comment was generated by todo based on a TODO comment in b38a46a in #4. cc @toxicafunk.