fix: Fetch data only if COMMIT_EDITMSG is empty
fix: Fetch data only if COMMIT_EDITMSG is empty

Changes made:
- request data only when current COMMIT_EDITMSG doesn't contain [branch]
- prepareCommitMessage method now takes branch arg
- promise's callbacks renamed due to shadowing path.resolve
- IncommingMessage import fixed

Fixes #2

Signed-off-by: Adrian Juszczak <a1b909ec1cc11cce40c28d3640eab600e582f833@juszczak.io>

Juszczak/git-jira