Change Do Not Bill to "Bill at X%"

[jtu0]

In order to have more granular control over how I bill when I'm not at the top of my game
As a freelancer
I want to be able to state a percentage to bill when logging time, instead of a "do or do not"

Possible Implementations

• Write a migration that adds a bill_percentage that defaults to 1.0, migrates the data forward in raw sql, then drops the do not bill column
• Add a percentage input field to the logging time section and default it to 100
• Find places that do the math to figure out billing times and convert them to use the percentage instead of the boolean. Make sure we are rounding to the quarter hour.