Make sure we have appropriate coverage report

This patch ensures that we have the following:
(1) Proper coverage report for all packages
(2) Build status and coverage percentage as part of README
(3) Add glide cache in travis.yml

.travis.yml

@@ -1,4 +1,6 @@
 language: go
+directories:
+    - $HOME/.glide/cache
 go:
   - 1.7
 

Makefile

@@ -78,21 +78,21 @@ bins: cherami-server cherami-replicator-server cherami-cli cherami-admin cherami
 
 cover_profile: bins
 	@echo Testing packages:
+	@mkdir -p $(BUILD)
+	@echo "mode: atomic" > $(BUILD)/cover.out
 	@for dir in $(TEST_DIRS); do \
 		mkdir -p $(BUILD)/"$$dir"; \
 		go test $(EMBED) "$$dir" $(TEST_ARG) -coverprofile=$(BUILD)/"$$dir"/coverage.out || exit 1; \
+		cat $(BUILD)/"$$dir"/coverage.out | grep -v "mode: atomic" >> $(BUILD)/cover.out; \
 	done
 
 cover: cover_profile
-	@for dir in $(TEST_DIRS); do \
-		go tool cover -html=$(BUILD)/"$$dir"/coverage.out; \
-	done
+	go tool cover -html=$(BUILD)/cover.out
 
 cover_ci: cover_profile
-	@for dir in $(TEST_DIRS); do \
-		goveralls -coverprofile=$(BUILD)/"$$dir"/coverage.out -service=travis-ci || echo -e "\x1b[31mCoveralls failed\x1b[m"; \
-	done
+	goveralls -coverprofile=$(BUILD)/cover.out -service=travis-ci || echo -e "\x1b[31mCoveralls failed\x1b[m"
 
 clean:
 	rm -f cherami-server cherami-replicator-server cherami-cli cherami-admin cherami-replicator-tool cherami-cassandra-tool
 	rm -Rf vendor/*
+	rm -Rf $(BUILD)

README.md

@@ -1,4 +1,4 @@
-cherami-server
+cherami-server [![Build Status](https://travis-ci.org/uber/cherami-server.svg?branch=master)](https://travis-ci.org/uber/cherami-server) [![Coverage Status](https://coveralls.io/repos/uber/cherami-server/badge.svg?branch=master&service=github)](https://coveralls.io/github/uber/cherami-server?branch=master)
 ==============
 [Cherami](https://eng.uber.com/cherami) is a distributed, scalable, durable, and highly available message queue system we developed at Uber Engineering to transport asynchronous tasks.