Rename behavior utility

[gbeane]

Note: branch name is misleading, should be rename-behavior-util

add cli utility for renaming a behavior in an existing JABS project

usage:

jabs-cli rename-behavior <project dir> <old behavior name> <new behavior name>

[SkepticRaven]

I like the new is_valid_project_directory method. I see a lot of project folders inside project folders because someone went into the jabs folder.

[gbeane]

@SkepticRaven

I like the new is_valid_project_directory method. I see a lot of project folders inside project folders because someone went into the jabs folder.

Yeah, I need to expand its use now -- especially for any command line tool that expects to operate on an existing JABS project directory so we avoid creating jabs directories if the user passes an incorrect path. For the GUI, I want users to be able to open a directory that's never been opened in JABS before but we could prompt for confirmation if it's not already a JABS project directory (or maybe for the GUI it would be more useful to check that the selected directory actually contains video/pose pairs)