[security-dev] common module in picketlink

[Marek Posolda]

I mentioned yesterday that it may be good to have something like 
separate "common" module, which will contain some stuff and 
functionalities, which may be needed across all other picketlink modules.

Example of such things could be:
- Class StringUtil from federation module (Some stuff in this class is 
specific to federation, but some common methods like 
StringUtil.isNotNull, StringUtil.getSystemPropertyAsString etc. are 
useful in other modules as well)
- Probably some other util classes in federation
- Some parts of logging
- Reflection and properties helper classes from IDM module
- Base64 util class (Currently we have same class forked two times in 
picketlink project. Once in "federation" module and once in "idm" module)
- Probably some more...

wdyt?
Marek