allow create and drop
pull in new thrift defs, delete thrift defs we didn't actually need
add insert
bump thrift
remove eden as a dependency
remove the buffer_length argument to Cursor.new (which was impossible to use anyway)
make Cursor#has_more? actually work.

impala currently seems to insist that it has more stuff in the table, right up
until the time it fetches zero rows. kinda annoying, but I think making the
extra call is worth it.
fetch data right off the bat, when a Cursor is instantiated.

This means the Cursor is no longer lazy in fetching data, but I'm not sure I
care. It fixes an issue where an cursor would return true for has_more? even if
there's nothing in the table.
add a bunch of connected tests (including ones for insert, create, drop)
bump version