Implement Secrets

Implement podman secret create, inspect, ls, rm
Implement podman run/create --secret
Secrets are blobs of data that are sensitive.
Currently, the only secret driver supported is filedriver, which means creating a secret stores it in base64 unencrypted in a file.
After creating a secret, a user can use the --secret flag to expose the secret inside the container at /run/secrets/[secretname]
This secret will not be commited to an image on a podman commit

Signed-off-by: Ashley Cui <acui@redhat.com>

docs/source/markdown/podman-secret-ls.1.md

@@ -0,0 +1,30 @@
+% podman-secret-ls(1)
+
+## NAME
+podman\-secret\-ls - List all available secrets
+
+## SYNOPSIS
+**podman secret ls** [*options*]
+
+## DESCRIPTION
+
+Lists all the secrets that exist. The output can be formatted to a Go template using the **--format** option.
+
+## OPTIONS
+
+#### **--format**=*format*
+
+Format secret output using Go template.
+
+## EXAMPLES
+
+```
+$ podman secret ls
+$ podman secret ls --format "{{.Name}}"
+```
+
+## SEE ALSO
+podman-secret(1)
+
+## HISTORY
+January 2021, Originally compiled by Ashley Cui <acui@redhat.com>