Few small changes suggested by prospector.

1) Few error-handeling modifications in the parser. The modifications
introduced are sufficient to avoid the crash of the code, but still are
not probably the best option. Discussion open in issue "Taxonomy of
failure modes #24"

2) Remove files in workflows/workfunction as they were not migreted
to aiida 1.0

aiida_siesta/parsers/siesta.py

@@ -33,7 +33,8 @@ def get_parsed_xml_doc(xml_path):
     try:
         xmldoc = minidom.parse(xml_path)
     except:
-        xmldoc = None
+        raise OutputParsingError("Faulty Xml File")
+        #xmldoc = None
 
     # We might want to add some extra consistency checks
 
@@ -156,7 +157,7 @@ def get_sizes_info(xmldoc):
                             int(s) for s in array.childNodes[0].data.split()
                         ]
 
-            return no_u, nnz, mesh
+    return no_u, nnz, mesh
 
 
 def get_last_structure(xmldoc, input_structure):
@@ -269,8 +270,6 @@ def get_final_forces_and_stress(xmldoc):
 ##################################
 
 
-from aiida.common.exceptions import OutputParsingError
-
 class SiestaOutputParsingError(OutputParsingError):
     pass
 
@@ -533,7 +532,7 @@ def get_bands(self, bands_path):
         tottx = f.read().split()
 
         ef = float(tottx[0])
-        if self.node.inputs.bandskpoints.labels == None:
+        if self.node.inputs.bandskpoints.labels is None:
             minfreq, maxfreq = float(tottx[1]), float(tottx[2])
             nbands, nspins, nkpoints = int(tottx[3]), int(tottx[4]), int(
                 tottx[5])