[MapD] Cast to float
[MapD] Cast to float

Resolves #1682

Author: Ivan Ogasawara <ivan.ogasawara@gmail.com>
Author: Phillip Cloud <cpcloud@gmail.com>

Closes #1737 from xmnlab/float_to_cast and squashes the following commits:

0f230c4 [Ivan Ogasawara] Changed text to str
1067428 [Ivan Ogasawara] Changed boolean to bool
7821cf9 [Phillip Cloud] Use test connect function in place of ibis.bigquery.connect
b47d3ad [Ivan Ogasawara] Changed INTEGER to INT
34c14c9 [Ivan Ogasawara] Resolves #1682

ibis-project/ibis,cpcloud/ibis,cloudera/ibis,cpcloud/ibis,cpcloud/ibis,ibis-project/ibis,ibis-project/ibis,cloudera/ibis,cpcloud/ibis,cloudera/ibis,ibis-project/ibis