ref(builder): replace python with bash

Debugging the builder script when it fails is really difficult in
python. You have to import a bunch of libraries, pipe stderr on some
commands to stdout, inspect the return codes and the error returned...
In short, it's quite difficult to debug. Refactoring to bash allows us
to debug the script quite easily by setting the -x option for bash
scripts and we have instant debugging.

This refactor also removes the "remote:" prefix from most of the
output, which is another huge plus.

fixes #1216 
fixes #1108 
@bacongobbler using your las commit sometimes I see that the list of environment variables are no a list (only the first element receive the "-e")

```bash
RESPONSE=$(curl -s -XPOST \
     -H "Content-Type: application/json" \
     -H "X-Deis-Builder-Auth: {{ .deis_controller_builderKey }}" \
     --data "{\"receive_user\":\"$USER\",\"receive_repo\":\"$APP_NAME\"}" \
     $URL | sed 's/\\"/"/g' | sed 's/"{/{/g' | sed 's/}"/}/g' )
# the sed is to return a valid json string.

# massage response for the environment variables in form HELLO=world
EXTRACT_VALUES=".values|to_entries|map(\"\(.key)=\(.value|tostring)\")|.[]"
CONFIG=$(echo $RESPONSE | jq -c -M $EXTRACT_VALUES 2> /dev/null || echo $RESPONSE)

if [ "$CONFIG" == "$RESPONSE" ];
then
    puts-warn "failed retrieving config from controller"
    puts-warn $RESPONSE
    exit 1
fi

# build option string to send to slugbuilder
BUILD_OPTS=""
echo $RESPONSE | jq -c -M $EXTRACT_VALUES | while read envvar; do
    if [ "$envvar" != "" ]; then
        BUILD_OPTS+="-e $envvar "
    fi
done
```