Update deps

vendor/github.com/shazow/go-diff/LICENSE

@@ -0,0 +1,22 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 Andrey Petrov
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+

vendor/github.com/shazow/go-diff/difflib/differ.go

@@ -0,0 +1,39 @@
+// This package implements the diff.Differ interface using github.com/mb0/diff as a backend.
+package difflib
+
+import (
+	"io"
+	"io/ioutil"
+
+	"github.com/pmezard/go-difflib/difflib"
+)
+
+type differ struct{}
+
+// New returns an implementation of diff.Differ using mb0diff as the backend.
+func New() *differ {
+	return &differ{}
+}
+
+// Diff consumes the entire reader streams into memory before generating a diff
+// which then gets filled into the buffer. This implementation stores and
+// manipulates all three values in memory.
+func (diff *differ) Diff(out io.Writer, a io.ReadSeeker, b io.ReadSeeker) error {
+	var src, dst []byte
+	var err error
+
+	if src, err = ioutil.ReadAll(a); err != nil {
+		return err
+	}
+	if dst, err = ioutil.ReadAll(b); err != nil {
+		return err
+	}
+
+	d := difflib.UnifiedDiff{
+		A:       difflib.SplitLines(string(src)),
+		B:       difflib.SplitLines(string(dst)),
+		Context: 3,
+	}
+
+	return difflib.WriteUnifiedDiff(out, d)
+}