changed __init__ of all sources to have an empty dictionary as default config value

FourmiCrawler/sources/ChemSpider.py

@@ -20,7 +20,7 @@ class ChemSpider(Source):
     somewhere.
     """
 
-    def __init__(self, config):
+    def __init__(self, config={}):
         Source.__init__(self, config)
 
     website = 'http://www.chemspider.com/*'

FourmiCrawler/sources/NIST.py

@@ -24,7 +24,7 @@ class NIST(Source):
 
     ignore_list = set()
 
-    def __init__(self, config):
+    def __init__(self, config={}):
         Source.__init__(self, config)
 
     def parse(self, response):

FourmiCrawler/sources/WikipediaParser.py

@@ -19,7 +19,7 @@ class WikipediaParser(Source):
     __spider = None
     searched_compounds = []
 
-    def __init__(self, config):
+    def __init__(self, config={}):
         Source.__init__(self, config)
 
     def parse(self, response):

FourmiCrawler/sources/source.py

@@ -6,7 +6,7 @@ class Source:
     website = "http://something/*"  # Regex of URI's the source is able to parse
     _spider = None
 
-    def __init__(self, config):
+    def __init__(self, config={}):
         """
         Initiation of a new Source
         """