Check chardet availability before using it

The use of chardet python library is quite useful in order to detect character encodings, but it's not installed in all systems by default. So, it's a good practice to check its availability before using it.

This pull request enhances shinken-monitoring#7

module/module.py

@@ -30,7 +30,10 @@
 except ImportError:
     MySQLdb = None
 
-import chardet
+try:
+    import chardet
+except ImportError:
+    chardet = None
 
 from shinken.basemodule import BaseModule
 from shinken.log import logger
@@ -140,7 +143,9 @@ def get_objects(self):
                     for column in row:
                         if row[column]:
                             value = str(row[column])
-                            h[column] = self.ensure_encoding(value)
+                            if chardet:
+                                value = self.ensure_encoding(value)
+                            h[column] = value
                     r[k].append(h)
 
         cursor.close()