Enable log prefix trimming for pass-through of logs from functions.

Changelog for 0.8.2:

• PR #121 Add mechanism to disable prefixes to function logs by @alexellis
• PR #120 Log some additional internal messages to stderr by @alexellis
• PR #119 Add docs in EnvVar section for mode by @Waterdrips

Commits
e338b8a Update Go version to 1.15 by @alexellis
664c2df Document prefix_logs feature by @alexellis
51ea0d6 Add mechanism to disable prefixes to function logs by @alexellis
6b710fb Log internal messages to stderr by @alexellis
6bee3ec Add docs in EnvVar section for mode by @Waterdrips

Generated by Derek