Report when build in progress

https://app.asana.com/0/11331512503351/13274569624686

After merge add this line to jenkins shell command before `virtualenv -q $VENV` statement:
```
curl "http://localhost:3000/jenkins/pre_build?user=percolate&repo=hotlanta&sha=$GIT_COMMIT&status=pending&job=$JOB_NAME&build=$BUILD_NUMBER"
```