Need a clean solution to read CCPP namelist option

[climbfuji]

PR #86 implements a workaround for reading the ccpp_suite namelist option before initializing CCPP physics. This is not an ideal solution, but given the upcoming changes wrt physics in the dycore, it minimizes the amount and frequency of changes that impact developers and users.

Background: The future implementation will use a generic interface in the dycore to either call the original GFDL fast physics (for SHIELD models etc) or the CCPP fast physics (for UFS etc), and will separate the existing suite definition files (SDFs) into two SDFs each (one for the dycore = fast physics, one for fv3atm = traditional physics). This means that we will have two ccpp_suite options in the namelist, one in the section relevant for the dycore (fv_core_nml?), one in the section relevant for physics (currently gfs_physics_nml). It doesn't make sense to change each namelist template in the repository and instruct all developers to change their namelists twice - better do it once.