Testsuite: moved tests directory to the root of the package.

Makefile.am

configure.in

src/testsuite/Makefile.am

tests/address-parts/subaddress.svtest

tests/comparators/core.svtest

tests/compile/compile-examples.svtest

tests/compile/compile.svtest

tests/compile/errors.svtest

tests/compile/errors/address-part.sieve

tests/compile/errors/address.sieve

tests/compile/errors/encoded-character.sieve

tests/compile/errors/envelope.sieve

tests/compile/errors/header.sieve

tests/compile/errors/if.sieve

tests/compile/errors/keep.sieve

tests/compile/errors/require.sieve

tests/compile/errors/size.sieve

tests/compile/errors/stop.sieve

tests/compile/redirect.sieve

tests/compile/trivial.sieve