update procfs to v0.0.2 (#1376)

Signed-off-by: Paul Gier <pgier@redhat.com>

vendor/github.com/prometheus/procfs/README.md

@@ -19,7 +19,14 @@ point is initialized, and then the stat information is read.
 
 ```go
 fs, err := procfs.NewFS("/proc")
-stats, err := fs.NewStat()
+stats, err := fs.Stat()
+```
+
+Some sub-packages such as `blockdevice`, require access to both the proc and sys filesystems.
+
+```go
+    fs, err := blockdevice.NewFS("/proc", "/sys")
+    stats, err := fs.ProcDiskstats()
 ```
 
 ## Building and Testing
@@ -30,7 +37,7 @@ changes to the library, the `make test` command can be used to run the API test
 ### Updating Test Fixtures
 
 The procfs library includes a set of test fixtures which include many example files from
-the `/proc` and `/sys` filesystems.  These fixtures are included as a ttar (text tar) file
+the `/proc` and `/sys` filesystems.  These fixtures are included as a [ttar](https://github.com/ideaship/ttar) file
 which is extracted automatically during testing.  To add/update the test fixtures, first
 ensure the `fixtures` directory is up to date by removing the existing directory and then
 extracting the ttar file using `make fixtures/.unpacked` or just `make test`.