Avoid importing slapos.libnetworkcache.

Instead use provided system level tools to generate keys.

src/zc/buildout/networkcache.txt

@@ -247,7 +247,14 @@ Now lets clean up buildout directory:
 Creating the signature files:
 
    >>> signature_data = tmpdir('signature_data')
-   >>> public_certificate_path, private_key_path = create_signature_file_list(signature_data)
+   >>> keydir = tmpdir('keydir')
+   >>> public_certificate_path = os.path.join(keydir, 'public.pem')
+   >>> private_key_path = os.path.join(keydir, 'private.pem')
+   >>> ignored = system(os.path.join(sample_buildout, 'bin', 'generate-signature-key') + ' --signature-certificate-file=' + public_certificate_path + ' --signature-private-key-file=' + private_key_path)
+   >>> ls(keydir)
+   -  private.pem
+   -  public.pem
+
 
 Enable signature, so it should not download any content which is not trusted :
    >>> write(sample_buildout, 'buildout.cfg',
@@ -328,7 +335,13 @@ Now lets clean up buildout directory:
    >>> remove('.installed.cfg')
 
 Now lets create new signature files:
-   >>> new_public_certificate_path, new_private_key_path = create_signature_file_list(signature_data, 'private2.pem', 'public2.pem')
+   >>> new_keydir = tmpdir('newkeydir')
+   >>> new_public_certificate_path = os.path.join(new_keydir, 'public2.pem')
+   >>> new_private_key_path = os.path.join(new_keydir, 'private2.pem')
+   >>> ignored = system(os.path.join(sample_buildout, 'bin', 'generate-signature-key') + ' --signature-certificate-file=' + new_public_certificate_path + ' --signature-private-key-file=' + new_private_key_path)
+   >>> ls(new_keydir)
+   -  private2.pem
+   -  public2.pem
 
 There is a new certificate file, so it should not download the old content:
    >>> write(sample_buildout, 'buildout.cfg',

src/zc/buildout/testing.py

@@ -389,15 +389,6 @@ def buildoutSetUp(test):
         register_teardown(lambda: stop_server(url, thread))
         return url
 
-    def create_signature_file_list(path,
-                                   private_key_file='private.pem',
-                                   certificate_file='public.pem'):
-        from slapos.signature import createPrivateKeyAndCertificateFile
-        private_key_file = os.path.join(path, private_key_file)
-        certificate_file = os.path.join(path, certificate_file)
-        createPrivateKeyAndCertificateFile(certificate_file, private_key_file)
-        return certificate_file, private_key_file
-
     def make_py(initialization=''):
         """Returns paths to new executable and to its site-packages.
         """
@@ -462,7 +453,6 @@ def buildoutSetUp(test):
         bdist_egg = bdist_egg,
         start_server = start_server,
         start_nc = start_nc,
-        create_signature_file_list = create_signature_file_list,
         buildout = os.path.join(sample, 'bin', 'buildout'),
         wait_until = wait_until,
         make_py = make_py,