add warning about SLZ assumption, output LAI
Resolved circular dependency and disabled broken tests

read.settings needs access to the database code, resulting in a
dependency on PEcAn.DB which in turn depends on PEcAn.utils
resulting in a circular dependency. Broke dependency by moving
read.settings to PEcAn.DB

disabled some read.output test in PEcAn.utils since it was testing
model specific code. (github #38)