tests: Divide SystemTestingSuite tests to Short/LongSystemTests

Existing tests division between sanity tests and other ones wasn't good enough.
Difficulties appeared when we wanted to check a major set of LizardFS features
but long tests would last too long (e.g. testing big changes just before
merging). This commit splits tests into two groups: "short" when each test
lasts up to ~5 minutes, "long" otherwise.

Change-Id: I7d2f1d41bdf52ae8f5d5d4f32c0fd5bc84fac8d3
master: Calculate fsnodes' checksums

To ensure metadata integrity when delegating dump to metarestore,
fsnodes' checksum is checked.

Change-Id: I7d17a50ee04d41e6c498218a5af93cb3114c09e0
master: Calculate fsedges' checksums

To ensure metadata integrity when delegating dump to metarestore,
fsedges' checksum is checked.

Change-Id: I585bee76909a737f80159225a412d26caddd2ca8