Only install softhsm and etcd in the test targets that need them (#1865)
Only install softhsm and etcd in the test targets that need them (#1865)

Only the integration tests for PKCS11 need softhsm installed, so skip
doing this for all of the other Travis test targets. Fixes #1851.

Only install etcd tools if we are running etcd in the tests. Installing
etcd tools takes >35s on some runs. This will save useless work for the
majority of targets.
RJPercival/trillian,gdbelvin/trillian,google/trillian,AlCutter/trillian,gdbelvin/trillian,AlCutter/trillian,gdbelvin/trillian,google/trillian,RJPercival/trillian