[All] Huge code & configuration cleanup and options refactoring

Configuration/options

 * ConfigToken has been renamed to Option to avoid collision with plain "configuration", such as Properties
 * All previous ConfigTokens from TableConfig and ColumnConfig have been gathered in a new DatatableOptions for an easier maintenance
 * Added a new OptionProcessingContext to hold all arguments needed during option processing and refactored all processor accordingly
 * All options have now a new precedence attribute, allowing to process a Option/value pair before another one.

General

 * Removed all integration tests from both datatables-jsp and datatables-thymeleaf cause they are now located in the dandelion-it module
 * Removed all customed RuntimeException and replaced them by the main DandelionException
 * Added loooots of comments

Dependencies

 * Cleaned up all POMs by removing all IT-related dependencies
 * Replaced FestAssert by AssertJ and updated all tests accordingly
 * Upgraded Thymeleaf to 2.1.3.RELEASE

Closes #254
Closes #258
Closes #261