Fix JDK8 incompatible comments

In JDK8 javadoc runs a lint pass over the documentation and fails if the docs
are not valid HTML. Also, see following article for a more in-depth 
discussion (http://blog.joda.org/2014/02/turning-off-doclint-in-jdk-8-javadoc.html)

Removed all occurrences of <br />,<p /> and replaced them with <br> and
<p>.
Require Maven-plugin-plugin version 3.3 

Reporting targets fail for dependants of the maven-plugin-plugin with
JDK 8, because the plugin generates invalid javadoc.
This has been fixed in version 3.3. 

Also see: https://jira.codehaus.org/browse/MPLUGIN-244
Sign contributor agreement
Add closing p tag

After discussion with sharell it turns out that some of the automated
 translation tools used for creating other ANTLR language targets look 
for closing tags (for one reason or another), so for this project 
the practice is to explicitly close all tags.
Merge pull request #719 from jeduden/master
Improved deterministic code generation output
Merge pull request #726 from sharwell/deterministic-output

Improved deterministic code generation output
improve debuggability of generated recognizer
improve management of test directories
improve test granularity
enable testing of javascript runtime in browsers
Merge pull request #728 from ericvergnaud/improve-debuggability

improve debuggability of generated recognizer
Merge pull request #731 from ericvergnaud/enable-browser-javascript-testing

enable testing of javascript runtime in browsers
Fixed a discarded test
Merge pull request #730 from ericvergnaud/improve-test-granularity

improve test granularity
Merge pull request #729 from ericvergnaud/improve-management-of-test-directories

improve management of test directories
Refactor and document configurable options for BaseTest
Create a test jar to assist in testing other language targets
Provide tokenNames to the code generator for improved compatibility with templates that haven't updated to the new Vocabulary interface
Merge pull request #736 from sharwell/codegen-tokennames

Provide tokenNames to the code generator