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.
Revert "pulling tarpaulin binary for travis instead of building"

This reverts commit b7e3bc467e483ec44e08fae1a97f1e5827acb7cb.
pulling tarpaulin binary for travis instead of building
updated readme
mentioned calling of $EDITOR
with opt-level=3, changed resulting binary size mentioned in notes
trimming whitespace
both when posting new item and when displaying items.
prevents posts from messing up the display of other
posts with extraneous whitespace.
left out install step for cargo-tarpaulin causing build failure
removed extraneous newline on post display
leave db intact on uninstall
updated deps + added release profile to Cargo.toml
using cargo tarpaulin instead of grcov
letting errors flow up