Fixes #9
Fixes #9

Now the explore class is a sub type of writable and has an explicit naming convention in it's output filename. ie: blah.explore.lkml

Co-Authored-By: bryan-at-looker <4b5dfdb2abf80b194c8033550533fc85b1890310@users.noreply.github.com>

looker-open-source/pylookml