resolve #232: open browser linux compatibility

@kevgo 

Able to test by overriding the `which` command to fake what tools are installed on the system.
I want to keep the mention of the browser at the beginning of the sentence since thats important and gives context to the rest of the sentence. Yes it sounds weird. I would like to just have the following:

```
Then my browser opens to a new Bitbucket pull request for the "feature" branch
```