Code-style, code-quality and comments improvements
Fix Maven warnings (plugin versions and encoding)
Reorder methods in classes into more logical order
Refactor BeanDefinitionParser
Fix POMs - declare all used dependencies

It's a good practice to declare *all used* dependencies, even those which are
pushed there by other dependency.
Exclude commons-logging from dependencies tree

Sice we're using slf4j, it should be used jcl-over-slf4j instead so
logging messages from commons-logging will go through slf4j.
Declare common dependencies in parent POM (DRY)
Merge pull request #6 from jirutka/cleanup

Some code-style, code-quality and comments improvements