[#1825] fix NPE in exception constructors when source files are not available (eg precompiled mode)

Introduce base class for all exceptions trying to access Java source files - PlayExceptionWithJavaSource that fixes this issue for all exceptions that now extend it.
Merge pull request #766 from codeborne/npe-without-source

[#1825] NPE is thrown when initializing some exception classes in precompiled mode