Get list properties working again

Get list properties working again

The CloudFormation documentation is very confusing on this point.
'CommaDelimitedList' is one of the data types that are valid for a
Parameter (the others are 'String' and 'Number'). A CommaDelimitedList
parameter takes the form of a string where the list members are delimted by
commas:

    "item1,item2,item3"

However the documentation also uses the phrase "Comma Delimited List" to
refer to the type of some Resource Properties that are, in fact, simply
lists:

    [ "item1" , "item2" , "item3" ]

...as if there were *another* way to represent lists. (Note that the
items here need not be strings, and in fact are usually objects of some
variety.)

So we need a different data type to represent the latter. (This patch
changes the name from 'TupleList' to just 'List', since the actual Python
sequence type is just an implementation detail.) In future, we should
probably also verify that only the 3 valid Parameter types are used, and
perhaps that list Properties contain only objects of the correct type.

Change-Id: I94054f588fc37f7d4ba245f2e92b86ac9c872c37
Signed-off-by: Zane Bitter <zbitter@redhat.com>