Use ebloom by default

This commit changes the default bloom filter to
be basho’s bloom, which is significantly more
stable w.r.t. performance.  The code can still
read the old bloom filters; new files are written
with the new filters.

The default is controlled in src/hanoidb.hrl
using the USE_EBLOOM macro.
Use new on-disk page format

This updates moves from kvlist to on-disk bisect
format (https://github.com/krestenkrab/vbisect)
which means that tree pages are not deserialised
when read form disk.  This improves performance
of GETs by ~20% and improves top-level latencies
significantly.

CRC32 checks are now on the page level.
Improve tests/dialyzing.
Add license for vbisect