Use https URLs

Add section about variables to README

Pass --quiet to psql

This ensures that only the query output is printed and any other output,
such as messages resulting from a .psqlrc file, are suppressed.

Merge pull request #4 from fphilipe/more-options

More options

Ignore empty STDIN

This happens when psql2csv is run in the context of another script that
happens to have STDIN open, e.g.:

    echo "psql2csv 'select 1'" | sh

set -e

Improve semicolon stripping

- only strip at end of file
- repeatedly strip until all trailing semicolons are gone

Add --dry-run flag

Use COPY instead of \copy

\copy is a wrapper around COPY which simply sets the output to STDOUT in
order to create a local file. Since we're outputting to STDOUT anyways,
there's no point in using \copy.

Strip trailing semicolon