Restructure charm to follow src dir format

The OpenStack reactive charms use a src directory to store the
'source' charm. Convert the vault charm to comply with this
structure.

Change-Id: I7dd36b9aa7419459238f989dfe6c0553f7641cdf

src/copyright

@@ -0,0 +1,16 @@
+Format: http://dep.debian.net/deps/dep5/
+
+Files: *
+Copyright: Copyright 2017, Canonical Ltd.
+License: GPL-3
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License version 3, as
+ published by the Free Software Foundation.
+ .
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranties of
+ MERCHANTABILITY, SATISFACTORY QUALITY, 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/>.

tox.ini

@@ -3,7 +3,7 @@
 # within individual charm repos.
 [tox]
 skipsdist = True
-envlist = pep8,py34,py35
+envlist = pep8,py34,py35,py36
 skip_missing_interpreters = True
 
 [testenv]
@@ -21,9 +21,8 @@ deps =
 
 [testenv:build]
 basepython = python2.7
-# Update when charm moves to src subdir
 commands =
-    charm-build --log-level DEBUG -o {toxinidir}/build . {posargs}
+    charm-build --log-level DEBUG -o {toxinidir}/build src {posargs}
 
 [testenv:py27]
 basepython = python2.7
@@ -43,11 +42,15 @@ basepython = python3.5
 deps = -r{toxinidir}/test-requirements.txt
 commands = ostestr {posargs}
 
+[testenv:py36]
+basepython = python3.6
+deps = -r{toxinidir}/test-requirements.txt
+commands = ostestr {posargs}
+
 [testenv:pep8]
 basepython = python3.5
 deps = -r{toxinidir}/test-requirements.txt
-# Update when charm moves to src subdir
-commands = flake8  --exclude build {posargs} .
+commands = flake8 {posargs} src unit_tests
 
 [testenv:venv]
 commands = {posargs}

unit_tests/__init__.py

@@ -1 +1,6 @@
 # unit tests
+
+import sys
+
+sys.path.append('src')
+sys.path.append('src/lib')