fix docker-build command (#1737)

Makefile

@@ -14,6 +14,12 @@ SIMAPP = ./app
 HTTPS_GIT := https://github.com/evmos/ethermint.git
 PROJECT_NAME = $(shell git remote get-url origin | xargs basename -s .git)
 DOCKER := $(shell which docker)
+NAMESPACE := tharsis
+PROJECT := ethermint
+DOCKER_IMAGE := $(NAMESPACE)/$(PROJECT)
+COMMIT_HASH := $(shell git rev-parse --short=7 HEAD)
+DOCKER_TAG := $(COMMIT_HASH)
+
 # RocksDB is a native dependency, so we don't assume the library is installed.
 # Instead, it must be explicitly enabled and we warn when it is not.
 ENABLE_ROCKSDB ?= false