Tools: Simplify log parser, add unit tests, fix bugs in corner cases

[gardner48]

• Simplify log parsing to remove use of ChainMap
• Use json.dumps to simplify printing log
• Add unit tests for parsing log files
• Fix bug in parsing lines where values contain =
• Fix bug in regex for lines where keys or values contain brackets
• Raise exception if updating a dictionary will overwrite an existing key
• Convert values to number when parsing payload
• Add better example of returned list in docs
• Add simple usage examples to doc strings