Use 'net-ftp-list' gem to parse ftp directory listing.

It also parses non-unix ftp servers, which have a different list format.
Merge pull request #426 from PetroFeed/ftpsite_whitespace_fix

Use 'net-ftp-list' gem to parse ftp directory listing.
Use boolify().
Fix #423 "cloud service" link broken
Fixed seeds and fictures for rain notifier

The seed rain notifier wasn't using liquid templates so the
conditions and location showed up as literal strings.
Merge pull request #428 from andrewcurioso/master

Fixed seeds and fixtures for rain notifier
Merge pull request #427 from CloCkWeRX/fix_423

Fix #423 "cloud service" link broken
Percent-encode unsafe characters in a filename when composing each URL.
RssAgent accepts `headers`, `basic_auth` and `user_agent`.

These options are provided by WebRequestConcern.
Make PostAgent use WebRequestConcern, adding options for Basic Auth and User-Agent.
Check if every request has a correct Content-Type.
Add some specs to compensate for the removed specs for generate_uri.
Enable Graphviz on Heroku.

Graphviz is installed via heroku-buildpack-graphviz-src and the location
of dot(1) is automatically added to PATH.

There is also heroku-buildpack-graphviz-deb which should be easier to
install, but the Debian package installed has a font style problem.
Merge pull request #431 from knu/heroku-graphviz

Enable Graphviz on Heroku.
Merge pull request #429 from knu/post_agent_faraday

Make PostAgent use WebRequestConcern, adding options for Basic Auth and User-Agent.
Fix the link path of each badge.
upgrade RSpec
Merge pull request #435 from cantino/upgrade_rspec

upgrade RSpec