Add a new timestamp.py file to the API directory (#409).

This is responsible for writing out a new times.toml file, containing
important timestamps in the life of a compose.  This seems a little more
reliable than attempting to infer things from the filesystem, especially
in light of the fact that we can't ever really know when a file was
created.

(cherry picked from commit b59d59b124)

src/pylorax/api/timestamp.py

@@ -0,0 +1,47 @@
+#
+# Copyright (C) 2018  Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import pytoml as toml
+import time
+
+from pylorax.sysutils import joinpaths
+
+def write_timestamp(destdir, ty):
+    path = joinpaths(destdir, "times.toml")
+
+    try:
+        contents = toml.loads(open(path, "r").read())
+    except IOError:
+        contents = toml.loads("")
+
+    if ty == "created":
+        contents["created"] = time.time()
+    elif ty == "started":
+        contents["started"] = time.time()
+    elif ty == "finished":
+        contents["finished"] = time.time()
+
+    with open(path, "w") as f:
+        f.write(toml.dumps(contents).encode("UTF-8"))
+
+def timestamp_dict(destdir):
+    path = joinpaths(destdir, "times.toml")
+
+    try:
+        return toml.loads(open(path, "r").read())
+    except IOError:
+        return toml.loads("")