updated travis cfg; setup Cargo.toml for crates.io
Added pertinent fields to Cargo.toml to publish on crates.io and
Updated .travis.yml - using bionic for build, tarpaulin binary can
now be pulled rather than built in-place.
updated deps + added release profile to Cargo.toml
now opens $EDITOR to write post body
logging reflects executing username
moved some functionality to module, added tests
moved display to 15 posts
ensure submitted posts are utf8
enabled deletion of posts
added functionality to update posts
enabled hints for cli args, changed db location
finished posting and display
added subtype to db::Cmd. Fleshed out cli args.