PLT-4357 adding performance monitoring (#4622)

* WIP

* WIP

* Adding metrics collection

* updating vendor packages

* Adding metrics to config

* Adding admin console page for perf monitoring

* Updating glide

* switching to tylerb/graceful

vendor/github.com/prometheus/common/config/testdata/tls_config.cert_no_key.bad.yml

@@ -0,0 +1 @@
+cert_file: somefile

vendor/github.com/prometheus/common/config/testdata/tls_config.insecure.good.yml

@@ -0,0 +1 @@
+insecure_skip_verify: true

vendor/github.com/prometheus/common/config/testdata/tls_config.invalid_field.bad.yml

@@ -0,0 +1 @@
+something_invalid: true

vendor/github.com/prometheus/common/config/testdata/tls_config.key_no_cert.bad.yml

@@ -0,0 +1 @@
+key_file: somefile