Use printError

Refs #58 , use `printError` instead of fmt.Print and friends
update heroku-go
a basic heroku postgresql client + simple pg-info
fix some categories
updated styleguide for category fixes
Commands for log drains.
show addons instead of URLs for those drains
add log-drain-info command, update styleguide
Put commands in `hk help more` if they go there.

These commands were listed in main.go as belonging in `hk help more`,
but they didn't actually have the bit that puts them there instead of in
the main help list. Fixes #62.
add runCommand to abstract path-finding part of running a command
pg-psql command
forgot pg_test.go
set client options on pgclient too
- Add a tab completion script for bash.
pg-psql -> psql

Fixes #67.
Remove `godep go get` command from instructions

This subcommand appears to have been deprecated, and doesn't seem to be
required to get `hk` to build:

```
Any go tool command can run this way, but "godep go get"
is unnecessary and has been disabled. Instead, use
"godep go install".
```
readme updates
short error message for unknown command

The full help text is long enough to be really annoying
now, especially if you're in the middle of something and
merely made a typo.
suggest spelling corrections for mistyped commands
Fix for shorthand db name args (i.e. "rose")

Thanks @dpiddy!