Add configuration for throws clause indentation

Checkstyle reports hundreds of errors for code like this (while being run from ant via CLI):
public void someMethodWithLongSignatureSoThrowsMovesToNextLine()
  throws SomeException

The earliest report about that is date 2008: http://en.it-usenet.org/thread/13413/346

https://github.com/checkstyle/checkstyle/pull/80 adds throwsIndent configuration parameter and finally resolves the issue.

See checkstyle's doc for more details http://checkstyle.sourceforge.net/config_misc.html#Indentation