Implement git-start

[dnelson]

Command: git-start [branch-name]

• takes an optional branch-name as an argument
• if no branch-name, shows list of possible jira tickets
• if still no branch-name, prompts for branch name as input
• syncs <main>
• creates new branch off of latest <main> with <username>/ prefix
• error handling ?

[lgodz15]

let's either leave the jira ticket step off or optional (somehow), since not everyone will be working with Jira (me included 🙃 )

[alainakafkes]

optional jira works for me :)

[dnelson]

I made a super basic PR for just sync and make a branch (#10). I have to research how the prefix stuff worked.