Enable ruby warnings
Eliminate warning “…/lib/timecop/timecop.rb:110: warning: instance variable @safe_mode not initialized”
Eliminate ‘not initialized’ warnings:
    “…lib/timecop/time_stack_item.rb:45: warning: instance variable @travel_offset not initialized”
	“…lib/timecop/time_stack_item.rb:49: warning: instance variable @scaling_factor not initialized”
Eliminate warning “lib/timecop/time_stack_item.rb:140: warning: mismatched indentations at 'end' with 'class' at 1”
Eliminate warning “…lib/timecop/time_extensions.rb:74: warning: method redefined; discarding old now.”

Could have used `undef :now’, but seems cleaner to alias :now_without_mock_time to be the old :now, rather than coding up an equivalent. (Same pattern as used in Time in this file)