Use terraform 0.11.13 and fix location

- Use TF_INSTALLATION_PREFIX in makefile
- Ignore .cache/ (local version of TF_INSTALLATION_PREFIX)
- Ignore config directories
- Ignore bundle installation directories

Author: Duologic

.gitignore

@@ -19,3 +19,7 @@ graph.png
 local-development-0/local-development-0.tfstate
 macstadium-*/config/
 tfstate
+.cache/
+config/
+.bundle/
+vendor/

terraform-common.mk

@@ -16,8 +16,8 @@ AMQP_URL_ORG_VARNAME ?= AMQP_URL
 TOP := $(shell git rev-parse --show-toplevel)
 NATBZ2 := $(TOP)/assets/nat.tar.bz2
 
-PROD_TF_VERSION := v0.11.10
-TERRAFORM := $(HOME)/.cache/travis-terraform-config/terraform-$(PROD_TF_VERSION)
+PROD_TF_VERSION := v0.11.13
+TERRAFORM := $(TF_INSTALLATION_PREFIX)/terraform-$(PROD_TF_VERSION)
 
 export PROD_TF_VERSION
 export TERRAFORM