Show the version of internal libraries before running tests

[ochaplashkin]

When testing different versions of internal libraries (for example, luatest), I want to see the versions of internal libraries when I run tests

Actual stdout

$ ./test-run.py --force --long
Started ./test-run.py --force --long
Running in parallel with 12 workers

Timeout options:
-------------------
SERVER_START_TIMEOUT:     90
REPLICATION_SYNC_TIMEOUT: 100
TEST_TIMEOUT:             110
NO_OUTPUT_TIMEOUT:        120

Collecting tests in 'app'            (Found 28  tests): application server tests.
Collecting tests in 'app-luatest'    (Found 55  tests): application server tests on luatest.

Expected stdout

$ ./test-run.py --force --long
Started ./test-run.py --force --long
Test-run version:  <version>
Luatest version: <version>
<Some library>: <version>
Running in parallel with 12 workers

Timeout options:
-------------------
SERVER_START_TIMEOUT:     90
REPLICATION_SYNC_TIMEOUT: 100
...