Enable tests for unicode for python, swift. (#2070)

Re-enable build swift/python containers (for tests to run).
Add unicode unit test for swift action container.
Allow for reinit with swift for use with invoke.py.
Fix unicode regression for swift actions.
Refactor unicode tests to add coverage - now also for base action container.
Set string encoding to utf-8 for swift action proxy.
Rewrite result extraction to avoid splitting and printing logs one line at a time.
Skip decoding when process output is a string; already utf-8.

Consolidate base64 encoding in CLI; remove Jar field in exec.