Cloned helper width

Fix:

In some situations cloned element wasn't automatically sized in the correct way and that was causing weird behavior. #28 by @inkassso

Now its width is copied from the original textarea element.

Rxjs operators

Small fixes:

• Correcting order of rxjs operators #27
• Setting content of the cloned textarea (issue with older browsers)

both things suggested by @Petronious

Respecting borders

New features:

• Taking top and bottom borders widths into consideration when calculating height of the textarea #24 by @nurfgun

force CSS !important

New features:

• Adding support for forcing css styles with '!important' #22 by @stephen-walcher