Update github.com/opencontainers/runtime-tools to v0.6.0

Also add new dependencies on github.com/xeipuuv/gojson* (brought up by
new runtime-tools) and adapt the containerd/cri code to replace the APIs
that were removed by runtime-tools.

In particular, add new helpers to handle the capabilities, since
runtime-tools now split them into separate sets of functions for each
capability set.

Replace g.Spec() with g.Config since g.Spec() has been deprecated in the
runtime-tools API.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>

vendor.conf

@@ -39,7 +39,7 @@ github.com/opencontainers/go-digest c9281466c8b2f606084ac71339773efd177436e7
 github.com/opencontainers/image-spec v1.0.1
 github.com/opencontainers/runc 69663f0bd4b60df09991c08812a60108003fa340
 github.com/opencontainers/runtime-spec v1.0.1
-github.com/opencontainers/runtime-tools 6073aff4ac61897f75895123f7e24135204a404d
+github.com/opencontainers/runtime-tools v0.6.0
 github.com/opencontainers/selinux 4a2974bf1ee960774ffd517717f1f45325af0206
 github.com/pkg/errors v0.8.0
 github.com/pmezard/go-difflib v1.0.0
@@ -54,6 +54,9 @@ github.com/stretchr/testify v1.1.4
 github.com/syndtr/gocapability db04d3cc01c8b54962a58ec7e491717d06cfcc16
 github.com/tchap/go-patricia 5ad6cdb7538b0097d5598c7e57f0a24072adf7dc
 github.com/urfave/cli 7bc6a0acffa589f415f88aca16cc1de5ffd66f9c
+github.com/xeipuuv/gojsonpointer 4e3ac2762d5f479393488629ee9370b50873b3a6
+github.com/xeipuuv/gojsonreference bd5ef7bd5415a7ac448318e64f11a24cd21e594b
+github.com/xeipuuv/gojsonschema 1d523034197ff1f222f6429836dd36a2457a1874
 golang.org/x/crypto 49796115aa4b964c318aad4f3084fdb41e9aa067
 golang.org/x/net b3756b4b77d7b13260a0a2ec658753cf48922eac
 golang.org/x/sync 450f422ab23cf9881c94e2db30cac0eb1b7cf80c