Fix fsnotify and apimachinery dependency errors

[johnmccabe]

The currently pinned dependencies have two problems that are highlighted when attempting to vendor new dependencies or reproduce the vendor directory from the Gopkg.lock file (I'd encountered these while investigating building on windows).

• hpcloud/tail has a transitive dependency to a no-longer existing repo.
• k8s.io/apimachinery pins to an invalid revision

If you wipe the vendor directory and attempt to reproduce it via dep ensure -v you should see something similar to the following:

(121/126) Wrote github.com/mailru/easyjson@dffba8d
(122/126) Wrote google.golang.org/grpc@v1.2.1
(123/126) Failed to write gopkg.in/fsnotify.v1@v1.4.2
(124/126) Failed to write k8s.io/kubernetes@v1.7.5
(125/126) Failed to write k8s.io/apimachinery@release-1.7
grouped write of manifest, lock and vendor: error while writing out vendor tree: failed to write dep tree: failed to export gopkg.in/fsnotify.v1: fatal: failed to unpack tree object 629574ca2a5df945712d3079857300b5e4da0236
: exit status 128

hpcloud/tail/fsnotify fix

This PR pins the hpcloud/tail dependency to the fix in the PR branch for hpcloud/tail#138 which addresses problems due to the fsnotify Github org name changing from go-fsnotify to fsnotify (see go-fsnotify/fsnotify#1).

This change also effectively bumps the vendored hpcloud/tail version to 1.4.7, no impact to CI tests have been observed.

When this upstream PR is merged we can point again at the hpcloud/tail repo.

k8s.io/apimachinery fix

This commit also addresses an issue introduced when migrating the dependencies from Rancher Trash to dep, the dep init used to populate the Gopkg.toml file had interpreted the pinned value for
k8s.io/apimachinery as a revision and not the branch which it pointed to.

The fix involves pinning k8s.io/apimachinery to the release-1.7 branch again in an override.

It should be possible to remove this when moving the k8s.io/kubernetes dependency to a version > 1.7.5 (there is no corresponding 1.7.5 tag on the apimachinery project, the earliest being 1.7.6).

[codecov]

Codecov Report

Merging #895 into master will increase coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #895      +/-   ##
==========================================
+ Coverage   48.53%   48.56%   +0.02%     
==========================================
  Files          84       84              
  Lines        7837     7837              
==========================================
+ Hits         3804     3806       +2     
+ Misses       3722     3721       -1     
+ Partials      311      310       -1

Impacted Files	Coverage Δ
pkg/types/spec.go	60.17% <0%> (+1.76%)	⬆️

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