Fixed bold issue

Bold would get "stuck" on in powershell/cmd prompt.

from clint.textui import colored

print colored.red("This will be normal")
print colored.red("This is bold", bold=True)
print "this will stay bold."

Would reproduce the issue. Seems that bold needs to be cleared after it is used, aka style has to be forced... It's a minor edit, maybe not an ideal fix, but this resolved it for me.