Config and result now have a Download button in the Crawl overview

This fixes #142
Empty form options are not handled anymore. Fixes #139
backward compatibility for TimeUnit rules
Merge pull request #145 from crawljax/backward-compat-for-timeunit

backward compatibility for TimeUnit rules
Merge pull request #144 from crawljax/issue-139-n-must-be-positive

Empty form options are not handled anymore.
Merge pull request #143 from crawljax/issue-142-config-download-button

Config and result now have a Download button in the Crawl overview
Merge remote-tracking branch 'origin/master' into issue-97-follow-all-hrefs

Conflicts:
	core/src/main/java/com/crawljax/browser/WebDriverBackedEmbeddedBrowser.java
	core/src/test/java/com/crawljax/browser/WebDriverBackedEmbeddedBrowserNoCrashTest.java