don't hardcod user in .gitconfig

set up a .bashrc-user that sets the GIT environmental variables

```
export GIT_AUTHOR_NAME="Brian Tingle"
export GIT_AUTHOR_EMAIL="brian.tingle@ucop.edu"
export GIT_COMMITTER_NAME="$GIT_AUTHOR_NAME"
export GIT_COMMITTER_EMAIL="$GIT_AUTHOR_EMAIL"
```