Make all packages lowercase.

var/spack/repos/builtin/packages/r-dbi/package.py

var/spack/repos/builtin/packages/r-rjava/package.py

var/spack/repos/builtin/packages/r-rmysql/package.py

var/spack/repos/builtin/packages/r-rodbc/package.py

var/spack/repos/builtin/packages/r-rpostgresql/package.py

var/spack/repos/builtin/packages/r-rsqlite/package.py

var/spack/repos/builtin/packages/r-xlconnect/package.py

var/spack/repos/builtin/packages/r-xlconnectjars/package.py

var/spack/repos/builtin/packages/unixodbc/package.py