Added Gopkg and updated README. This is v1.0.0

Author: chewxy

.gitignore

@@ -22,3 +22,6 @@ _testmain.go
 *.exe
 *.test
 *.prof
+
+# vendor
+/vendor

.travis.yml

@@ -5,9 +5,11 @@ branches:
     - master
 
 go:
-  - 1.5.4
-  - 1.6.3
-  - 1.7.3
+  - 1.5.x
+  - 1.6.x
+  - 1.7.x
+  - 1.8.x
+  - 1.9.x
   - tip
 
 env:

Gopkg.lock

@@ -0,0 +1,35 @@
+
+# Gopkg.toml example
+#
+# Refer to https://github.com/golang/dep/blob/master/docs/Gopkg.toml.md
+# for detailed Gopkg.toml documentation.
+#
+# required = ["github.com/user/thing/cmd/thing"]
+# ignored = ["github.com/user/project/pkgX", "bitbucket.org/user/project/pkgA/pkgY"]
+#
+# [[constraint]]
+#   name = "github.com/user/project"
+#   version = "1.0.0"
+#
+# [[constraint]]
+#   name = "github.com/user/project2"
+#   branch = "dev"
+#   source = "github.com/myfork/project2"
+#
+# [[override]]
+#  name = "github.com/x/y"
+#  version = "2.4.0"
+
+ignored = ["github.com/alecthomas/assert"]
+
+[[constraint]]
+  name = "github.com/pkg/errors"
+  version = "0.8.0"
+
+[[constraint]]
+  name = "github.com/stretchr/testify"
+  version = "1.1.4"
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/xtgo/set"

Gopkg.toml

@@ -6,7 +6,7 @@ Package hm is a simple Hindley-Milner type inference system in Go. It provides t
 
 This package is go-gettable: `go get -u github.com/chewxy/hm`
 
-There are very few dependencies that this package uses. Therefore there isn't a need for vendoring tools.
+There are very few dependencies that this package uses. Therefore there isn't a need for vendoring tools. However, package hm DOES provide a `Gopkg.toml` and `Gopkg.lock` for any potential users of the [dep](https://github.com/golang/dep) tool.
 
 Here is a listing of the dependencies of `hm`: