Implemented actions reject and vacation.

sieve/tests/vacation.sieve

src/lib-sieve/cmd-redirect.c

src/lib-sieve/ext-reject.c

src/lib-sieve/plugins/vacation/ext-vacation.c

src/lib-sieve/sieve-actions.c

src/lib-sieve/sieve-actions.h

src/lib-sieve/sieve-address-parts.c

src/lib-sieve/sieve.h

src/sieve-bin/sieve-exec.c

src/sieve-bin/sieve-test.c