master: Make the master start faster with empty metadata

This change will make short tests much faster, because mfsmaster without
this patch doesn't accept connections for up to 10 seconds after it was
started (look at the "starting" variable in matoclserv.cc).
master: Set minimum chunk loop time to 1 second

This makes it possible to set CHUNKS_MIN_LOOP_TIME and
CHUNKS_LOOP_TIME to one second in tests and during
development to speed up chunk operations.
tests: Introduce functional tests

This commit intruduces a testing framework for functional tests
of the filesystem together with some simple tests. The framework
allows users to create tests (in Bash) which setup the whole installation
consisting of many chunkservers and do some checks using it.