fix kherge/Amend dependency
Added initial version of contribution guidelines.

Largely based on the great writeup at https://github.com/FriendsOfSymfony/FOSJsRoutingBundle/blob/master/CONTRIBUTING.md.
Fix description for CLI option to set default value of construction parameters to null.
Merge pull request #107 from kasperg/fix-constructor-null-description

Fix description for constructorNull CLI option
Split contribution guidelines into pull requests and issues.
Add support for base types

Add main schema to schema array so that it would be possible to search base types and nillable members also in main wsdl file(s)

Add support for custom XML Schema prefix
Remove dependency on type order for inheritance.

- Update test case to check for type order independency.
- Move test incomplete marker and check for abstract case to the bottom
of test case to make test fail if random type order is not supported.
- Check for inheritance after all classes have been loaded.
- Load base classes where needed to avoid dependency on order in Service class.
Add abstract test case.

This tests handling of abstract and extended classes.

The test is currently incomplete as the code does not handle this properly.
Refactor Validator.

Move all name changes caused by validation to Validator class. This means we no longer need the ValidationException class.

Simplify Validator class methods. There is no need to separate class/operation/etc. validation from name validation.

Added methods to validate constant and attribute names.
Fix location of type nodes if no prefix is used.
Code style fixes
Merge pull request #104 from kasperg/contributing

Added initial version of contribution guidelines.
Merge branch 'base-type-support'
Refactor generator.

The result should be that the code is in a better state so we can create a new release containing base type support. We should also have a better base for adding new features which depend on extracting information from WSDL and XSD files.

I have tried to move all XML handling and querying into classes under the Xml namespace and created classes representing the different elements of the schema that we are interested in.

These classes consist of two parts:

- The metadata for the elements as returned by the PHP SoapClient
- Their corresponding XML element.

I used DOMDocument for parsing WSDL and XSD files. I would have liked to use SimpleXML but I could not get their XPath implementation to work as expected.

I have tested the refactoring by comparing the output of tests before and after. They are 99% identical. The only difference I see is that 2 places (like here) elements are now detected properly as nillable. Consequently they are no longer part of the constructor arguments. I consider this a bug fix.
Updated PHPUnit to 4.0.x and other dependencies.
Added Lafriks to list of contributors.
Release 2.4.0
Allow phpunit to use all 4.x releases.

Updated dependencies.
Use 4 spaces as indention, as requested by PSR-2
Merge pull request #114 from xstefanox/feature/psr2-compliant-indention

Use 4 spaces as indention, as requested by PSR-2