Minor CQL3 fixes

The goal of this ticket is to be the home for a number of minor fixes/improvements in CQL3 that I didn't felt warranted a ticket each. It includes 4 patches:

• The first one fixes the grammar for float constants, so as to not recognize 3.-3, but to actually allow 3. (i.e, with radix point but with the fractional part left blank)
• The second one correctly detect the (invalid) case where a table is created with COMPACT STORAGE but without any 'clustering keys'.
• The third one fixes COUNT, first by making sure both COUNT and COUNT(1) are correctly recognized and also by "processing" the internal row before counting, are there isn't a 1-to-1 correspondence between internal rows and CQL rows in CQL3. The grammar change in this patch actually rely on CASSANDRA-4184
• The fourth and last patch disallows the counter type for keys (i.e. any column part of the PRIMARY KEY) as it is completely non-sensical and will only led to confusion.