Transferred decoupled 2p2c fluidstate into more consequent file naming to...

Transferred decoupled 2p2c fluidstate into more consequent file naming to please Christoph even more. This became possible because there is no more 2p2cfluidstate in the box models.
Reviewer Christoph

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@8396 2fb0f335-1f38-0410-981e-8018bf24f1b0