Revert Go dep to 1.9

Ping GH-4028

.travis.yml

@@ -7,7 +7,7 @@ services:
   - docker
 
 go:
-  - "1.10"
+  - "1.9"
 
 matrix:
   allow_failures:

CHANGELOG.md

@@ -4,10 +4,14 @@ IMPROVEMENTS:
 
  * auth: Allow sending default_lease_ttl and max_lease_ttl values when enabling
    auth methods. [GH-4019]
+ * secret/database: Add list functionality to `database/config` endpoint
+   [GH-4026]
 
 BUG FIXES:
 
- * auth/aws: Switch libraries to fix regression verifying PKCS#7 identity
+ * listener: Revert to Go 1.9 for now to allow certificates with non-DNS names
+   in their DNS SANs to be used for Vault's TLS connections [GH-4028]
+ * auth/aws: Update libraries to fix regression verifying PKCS#7 identity
    documents [GH-4014]
 
 ## 0.9.4 (February 20th, 2018)

README.md

@@ -59,7 +59,7 @@ Developing Vault
 --------------------
 
 If you wish to work on Vault itself or any of its built-in systems, you'll
-first need [Go](https://www.golang.org) installed on your machine (version 1.10+
+first need [Go](https://www.golang.org) installed on your machine (version 1.9+
 is *required*).
 
 For local dev first make sure Go is properly installed, including setting up a