Fix deployment Makefile goal

The virtual environment virtual directory wasn't set properly for
deployment.
Fixes #21

Makefile.global

@@ -1,6 +1,7 @@
 SELF_DIR         := $(dir $(lastword $(MAKEFILE_LIST)))
-EXTENSION        = crankshaft
-PACKAGE          = crankshaft
-EXTVERSION       = $(shell grep default_version $(SELF_DIR)/src/pg/$(EXTENSION).control | sed -e "s/default_version[[:space:]]*=[[:space:]]*'\([^']*\)'/\1/")
-RELEASE_VERSION ?= $(EXTVERSION)
-SED              = sed
+EXTENSION         = crankshaft
+PACKAGE           = crankshaft
+EXTVERSION        = $(shell grep default_version $(SELF_DIR)/src/pg/$(EXTENSION).control | sed -e "s/default_version[[:space:]]*=[[:space:]]*'\([^']*\)'/\1/")
+RELEASE_VERSION  ?= $(EXTVERSION)
+SED               = sed
+VIRTUALENV_PATH  := $(realpath $(SELF_DIR)/envs)