Extracted interfaces from Parser and PageFetcher in order to make it easier to create totally custom classes

Made a silly change in an error in javadoc in order to make a commit and pass the merge checks again, now that the bug in java8 checks is fixed in repo

There was an http fetch error on Java11 test. Commit to pass the test again

This modification would allow to use a database other than sleepycat easilly.

Allows to use any implementation for the DocIDServer, not only sleepycat

Very basic selenium integration. This is not intended to be a full selenium crawler like Nutch, the main goal is to provide a simple way to crawl full-js pages without directly calling the REST APIs. If you're trying to navigate simple HTML pages with, lets say, a POST form, I'd recommend using the POST Capabilities MR instead

Connections stablished through selenium are not counted in the same pool than those opened with HttpClient, so limitations are not taken into consideration. Further commits will attemp to resolve this issue, but it is not straight-forward.

Selenium request will NOT be intercepter by the credentials interceptors, and cookies obtained via FormLogin (or any other non-selenium request) will not be visible for selenium browser.

You can define inclussions / exclussions on the new SeleniumCrawlConfig class to determine which URLs will be visited using Selenium and which won't. Starting with a Selenium seed is not possible at the moment (although it would be possible using the  new functions created in my POST CAPABNILITIES MR, which allow to pass WebURLs to addSeed methods.

Please, note that Selenium API does NOT provide headers information, so they won't be available in the Page class.

A full selenium integration would require to modify the crawler too deeply, but right now, the active selenium headless browser window is available through page#getFetchedResult. This is a bit unconvenient as it forces you to perform instanceof verifications in order to access it.

Selenium now sees the cookies generated by HttpClientRequest and vice-versa

All Selenium classes are now in a new package