fission/builder image, log collection improvement in builder (#397)

Create a container image with the buidler, so we can avoid copying the builder binary into the env container during the env container build. 

Gather both stdout and stderr of a build into the logs.
 

* Add Dockerfile for builder + update release scripts

* Improve logging of buildermgr and builder

* Add support for environment-scoped buildcmd

* Fix fork/exec wd when package is a file

* Update tests to also include builder image

* Add logging to builder's fork/exec

test/build_and_test.sh

@@ -14,19 +14,22 @@ REPO=gcr.io/fission-ci
 IMAGE=$REPO/fission-bundle
 FETCHER_IMAGE=$REPO/fetcher
 FLUENTD_IMAGE=gcr.io/fission-ci/fluentd
+BUILDER_IMAGE=$REPO/builder
 TAG=test
 
+dump_system_info
+
 build_and_push_fission_bundle $IMAGE:$TAG
 
 build_and_push_fetcher $FETCHER_IMAGE:$TAG
 
-build_builder
+build_and_push_builder $BUILDER_IMAGE:$TAG
 
 ENV='python'
 
 build_and_push_env_runtime $ENV $REPO/$ENV-env:$TAG
 
-build_and_push_env_builder $ENV $REPO/$ENV-env-builder:$TAG
+build_and_push_env_builder $ENV $REPO/$ENV-env-builder:$TAG $BUILDER_IMAGE:$TAG
 
 build_and_push_fluentd $FLUENTD_IMAGE:$TAG