Allow additional arguments to be passed into hooks

If a packager wants to be able to support addititional arguments on his
hook this will allow them to setup the configuration with these arguments.

For example this would allow a hook developer to add support for a --debug
flag to change the level of debugging in his hook.

In order to complete this task, I had to vendor in the latest
github.com://opencontainers/runtime-tools, which caused me to have to fix a
Mount and Capability interface calls

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

vendor/github.com/xeipuuv/gojsonschema/jsonContext.go

@@ -0,0 +1,72 @@
+// Copyright 2013 MongoDB, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// author           tolsen
+// author-github    https://github.com/tolsen
+//
+// repository-name  gojsonschema
+// repository-desc  An implementation of JSON Schema, based on IETF's draft v4 - Go language.
+//
+// description      Implements a persistent (immutable w/ shared structure) singly-linked list of strings for the purpose of storing a json context
+//
+// created          04-09-2013
+
+package gojsonschema
+
+import "bytes"
+
+// jsonContext implements a persistent linked-list of strings
+type jsonContext struct {
+	head string
+	tail *jsonContext
+}
+
+func newJsonContext(head string, tail *jsonContext) *jsonContext {
+	return &jsonContext{head, tail}
+}
+
+// String displays the context in reverse.
+// This plays well with the data structure's persistent nature with
+// Cons and a json document's tree structure.
+func (c *jsonContext) String(del ...string) string {
+	byteArr := make([]byte, 0, c.stringLen())
+	buf := bytes.NewBuffer(byteArr)
+	c.writeStringToBuffer(buf, del)
+
+	return buf.String()
+}
+
+func (c *jsonContext) stringLen() int {
+	length := 0
+	if c.tail != nil {
+		length = c.tail.stringLen() + 1 // add 1 for "."
+	}
+
+	length += len(c.head)
+	return length
+}
+
+func (c *jsonContext) writeStringToBuffer(buf *bytes.Buffer, del []string) {
+	if c.tail != nil {
+		c.tail.writeStringToBuffer(buf, del)
+
+		if len(del) > 0 {
+			buf.WriteString(del[0])
+		} else {
+			buf.WriteString(".")
+		}
+	}
+
+	buf.WriteString(c.head)
+}