Fix boilerplate

With charm-tools>=2.8 the build output folder layout
has changed.
Also the linter will fail if the actions/ folder doesn't
exist.
Also put the right flake8 in the right *requirements.txt
file.

Change-Id: Iad6603ef9cecefddbe88766580112191c0472a35

requirements.txt

@@ -1,4 +1,3 @@
 # Requirements to build the layer
-charm-tools
+charm-tools==2.8.3
 simplejson
-flake8

test-requirements.txt

@@ -1,2 +1,2 @@
-flake8>=2.2.4,<=2.4.1
+flake8>=2.2.4
 os-testr>=0.4.1

tox.ini

@@ -28,7 +28,7 @@ basepython = python3
 commands =
   /bin/echo 'WARNING: *build* target is for testing only.'
   /bin/mkdir -p {envdir}/tmp
-  charm-build --log-level DEBUG -o {envdir}/tmp/build .
+  charm-build --log-level DEBUG -o {envdir}/tmp/build/builds .
   /bin/ln -s {envdir}/tmp/build/builds {envdir}/tmp/build/trusty
   /bin/ln -s {envdir}/tmp/build {toxinidir}/build
 
@@ -62,4 +62,5 @@ commands = /bin/true
 
 [testenv:pep8]
 basepython = python3
+deps = -r{toxinidir}/test-requirements.txt
 commands = flake8 --ignore=E402 actions/ reactive/