facho: clip.py se adiciona nuevo comand 'sign-xml'.

* facho/cli.py: adiciona nuevo comando 'sign-xml' para firmar
directamente un xml.
* facho/fe/fe.py (DianXMLExtensionSigner.sign_xml_string): Nuevo metodo.

FossilOrigin-Name: 61920c40da14a134de6392845b3e4d98ad2b1b683093038d6161c147669127e9

tests/test_fe.py

@@ -94,5 +94,15 @@ def test_dian_invoice_with_fe():
     assert "<Invoice" in xml.tostring()
 
 
+def test_xml_sign_dian(monkeypatch):
+    xml = fe.FeXML('Invoice',
+                'http://www.dian.gov.co/contratos/facturaelectronica/v1')
+    xmlstring = xml.tostring()
+    signer = fe.DianXMLExtensionSigner('./tests/example.p12')
+    
+    with monkeypatch.context() as m:
+        helpers.mock_urlopen(m)
+        xmlsigned = signer.sign_xml_string(xmlstring)
+    assert "Signature" in xmlsigned