TLV_IE_Collection: use snake-style names during from_dict()

The TLV_IE_Collection, just like the individual TLV classes, do
use their snake-style names when converting from binary to dict
using the to_dict() method.  It is inconsistent (and a bug) to
expect the CamelCase names during encoding (from_dict).  After all,
we want the output of to_dict() to be used as input to from_dict().

Change-Id: Iabd1ad98c3878659d123eef919c22ca824886f8a
diff --git a/pySim/tlv.py b/pySim/tlv.py
index bd95505..22a14cd 100644
--- a/pySim/tlv.py
+++ b/pySim/tlv.py
@@ -318,7 +318,7 @@
         self.members_by_tag = {}
         self.members_by_name = {}
         self.members_by_tag = {m.tag: m for m in self.members}
-        self.members_by_name = {m.__name__: m for m in self.members}
+        self.members_by_name = {camel_to_snake(m.__name__): m for m in self.members}
         # if we are a constructed IE, [ordered] list of actual child-IE instances
         self.children = kwargs.get('children', [])
         self.encoded = None