Fix memory leak by freeing options we allocated

[mgreter]

Needs sass/libsass#2213

Allocated on line 230 by sass_make_options

[mgreter]

# valgrind --leak-check=full sassc/bin/sassc sassc/foo.scss
==3514== Memcheck, a memory error detector
==3514== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==3514== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==3514== Command: sassc/bin/sassc sassc/foo.scss
==3514==
foo-bar {
  baz: baz; }
==3514==
==3514== HEAP SUMMARY:
==3514==     in use at exit: 0 bytes in 0 blocks
==3514==   total heap usage: 2,403 allocs, 2,403 frees, 166,497 bytes allocated
==3514==
==3514== All heap blocks were freed -- no leaks are possible
==3514==
==3514== For counts of detected and suppressed errors, rerun with: -v
==3514== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)