Add AssertionProvider and assertions-EN.properties

AssertionProvider parses 'src\main\resources\assertions-EN.properties' and
and creates definitions for assertions. The definitions are used by Check.
Assertion definitions can now be updates without modifiying the project
source code.
Add dependency on jericho-html-3.3

The old HTML parser, jsoup, will be eventually removed.
Merge branch 'assertion-properties'
Update to remove jsoup HTML parser