Refactored into multiple classes

This commit refactors the single oracle::xe class into multiple classes.
Also parameterizes some stuff (file names, etc.).
Removed extra oracle-xe start

Added check for whether oracle-xe has been updated-rc.d'd.
Added oracle::service class.
Use template for xe.rsp

This commit changes the hard-coded xe.rsp (response file for Oracle
configuration) to an erb template and modifies the oracle::install class
to generate xe.rsp from the template.