The previous approach used ex_reg_valid to determine whether to
source data from the FPU or RoCC.  Thus, when the RoCC was not
present, it was still creating muxes.  Using ex_cp_valid instead
gets rid of them.

Closes #228.

In commit 3f8c60bb I inadvertently
changed the configuration while refactoring it.

Ideally, chisel should flag this as an error.

Allow some External Interrupts to come from Periphery

Streamline the Generator App and associated utilities. Remove deprecated call to chiselMain and useless Chisel2 args. Update arguments to sbt run. (#227)

Remove openocd from .gitmodules

Adds Logic & test support for JTAG implementation of Debug Transport Module.

This doesn't get added to Travis, but this target can be used
by other automated testing tools which may want to do further
testing on rocket-chip.

Conflicts:
	src/main/scala/rocketchip/TestHarness.scala

Test harness fixes

enable the TestDriver to be used in a SystemVerilog UVM-based testbench, which has its own way to manage end-of-simulation and does not like anyone else to call $finish