Implemented test LG25.

[porterclev]

Description

Team from CodeDay implementing LG25. PR contains:

• Implementation of code for LG25: "should have daily points for 15 + 20 minute reading intervals and flow units with +-inf start/end time & thing as thing where rate is 36"
• Included relevant test data CSV

Fixes #962

Type of change

• [ ] Note merging this changes the database configuration.
• [x] This change requires a documentation update

Checklist

• [x] I have followed the OED pull request ideas
• [x] I have removed text in ( ) from the issue request
• [x] You acknowledge that every person contributing to this work has signed the OED Contributing License Agreement and each author is listed in the Description section.

[sibyl]

Wrong sibyl. No idea what this is!

[huss]

Wrong sibyl. No idea what this is!

@sibyl I'm sorry. It should have been @SibylYang. Thanks for letting me know.