Fix mixing C and C++ in templates

This kills the favorite error for some gcc versions about C in the
templates.

*snip*
/usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/include/g++-v4/bits/basic_string.tcc:1068:3:
error: template with C linkage
make[2]: *** [zypp/CMakeFiles/zypp.dir/parser/xml/Node.cc.o] Error 1
*snip*

Basically we don't need to put this stuff here as it is done in the
headers themselves, so just prune the problematic code.
Fix missing include of iostream

As without it the test just happily fails to compile due to this:

tests/zypp/Flags_test.cc:9:12: error: ‘std::cout’ has not been declared
Merge pull request #20 from scarabeusiv/master

Fix mixing C and C++ in templates