travis: Add go 1.7 and drop go 1.5 support. (#740)

.travis.yml

@@ -1,15 +1,12 @@
 language: go
 go:
-  - 1.5.4
   - 1.6.3
+  - 1.7
 sudo: false
-before_install:
-  - gotools=golang.org/x/tools
-  - export GO15VENDOREXPERIMENT=1
 install:
   - go get -v github.com/Masterminds/glide
   - glide install
-  - go get -v $gotools/cmd/cover
+  - go get -v golang.org/x/tools/cmd/cover
   - go get -v github.com/golang/lint/golint
 script:
   - export PATH=$PATH:$HOME/gopath/bin

README.md

@@ -33,7 +33,7 @@ which are both under active development.
 
 ## Requirements
 
-[Go](http://golang.org) 1.5 or newer.
+[Go](http://golang.org) 1.6 or newer.
 
 ## Installation
 
@@ -58,10 +58,6 @@ recommended that `GOPATH` is set to a directory in your home directory such as
 `~/goprojects` to avoid write permission issues.  It is also recommended to add
 `$GOPATH/bin` to your `PATH` at this point.
 
-**NOTE:** If you are using Go 1.5, you must manually enable the vendor
-experiment by setting the `GO15VENDOREXPERIMENT` environment variable to `1`.
-This step is not required for Go 1.6.
-
 - Run the following commands to obtain btcd, all dependencies, and install it:
 
 ```bash

docs/README.md

@@ -85,10 +85,6 @@ recommended that `GOPATH` is set to a directory in your home directory such as
 `~/goprojects` to avoid write permission issues.  It is also recommended to add
 `$GOPATH/bin` to your `PATH` at this point.
 
-**NOTE:** If you are using Go 1.5, you must manually enable the vendor
-experiment by setting the `GO15VENDOREXPERIMENT` environment variable to `1`.
-This step is not required for Go 1.6.
-
 - Run the following commands to obtain btcd, all dependencies, and install it:
 
 ```bash