p1: /v2/scrape, /v1/fetch, auth, CLI, contract tests

Single Fetcher.Fetch on the Guard that holds DenyPrefixes. skipTlsVerification
is ignored. No 502. keys add writes the secret only to --out. Release binary
has no -test-allow-prefix.

vendor/github.com/andybalholm/cascadia/.travis.yml

@@ -0,0 +1,14 @@
+language: go
+
+go:
+  - 1.3
+  - 1.4
+
+install:
+  - go get github.com/andybalholm/cascadia
+
+script:
+ - go test -v
+
+notifications:
+  email: false