utils: Introduce wireshark plugin

This commit adds sources of a dissector of our protocol which
can be used with wireshark. The source code of this dissector
is generated automatically from comments in the MFSCommunication.h
file (to achieve this the file was slightly modified).
tests: Add expect_* and assert_* functions

This commit adds some useful functions which can substitute common
patterns existing in tests, eg:

if ! some_command [args]... ; then
  test_fail "blah blah blah"
fi
master: Fix segfault when unlinking files

When the master server starts with the empty filesystem it doesn't initialize
one of the lists properly. This issue causes a segfault when unlink operation
is performed shortly after starting the master server with empty metadata.
tests: Add test_compilation_and_rsync

This tests checks if it is possible to successfully use some common tools
on LizardFS. These tools include: git, cmake, g++, rsync.