This refactors everything to generate and use a flux AST when
transpiling an influxql query. This also updates the spectests so they
use flux instead of writing out the AST and compare the resulting
AST's.
I did this with a dumb editor macro, so some comments changed too.
Also rename root package from platform to influxdb.
In interest of minimizing risk, anyone importing the root package has
now aliased it to "platform" so that no changes beyond imports were
necessary in those files.
Lastly, replace the old platform module to local path /dev/null so that
nobody can accidentally reintroduce a platform dependency while
migrating platform code to influxdb.
* Add default column to databases to support `show retention policies`
* add unit test for show retention policies
* update transpiler readme for show databases, show retention policies
Jonathan A. Sternberg
Nathaniel Cook
Mark Rushakoff
Adam