gh-613 replication conflict test cases

gh-613 after review fixes

microsleep for CRDT test case, test-run updated

CRDT fix

finalizers.test marked as long run in suite

 *) added stress test for snapshotting
 *) moved finalizers.test.py to long_run

set test-run module in gh-3 branch for review

closes gh-856

Backport fix from tarantool/mysql by Anton Reznikov

Implement box.once().

Right now there is a race in box.once(), this is somethign we'll
need to fix when we have master election on simultaneous bootstrap.

The patch merely "establishes" the syntax which is going to work
most of the time.

Don't log exceptions of dead joinable fibers - it will
be logged by the caller, so avoid double logging.

recover_remaining_wals() is now more like an iterator,
vclockset_match() is only called when there is no current WAL.

Add a test case for gaps in LSNs.

Add a directory watcher, in addition to the file watcher.

Chagne wal_dir_rescan_delay default value to 2, since now it's
merely a backup.

Fix a crash in rollbackStatement() when rolling back a
statement trying to access a non-exissting space.

space_cache_find() is called before txn_begin_stmt(), thus
there is no statement object, nothing to roll back.

Remove iditioc tests from the suite.

Change the logic of recovery_finalize() to open
the next xlog if the last xlog had zero rows.
Add a test case.

Remove recovery->finalize, use recovery->writer instead.

Hard-code 1-based error message for now, we'll use field names
in the future anyway.

Remove trailing spaces, fix typos.

Old sql code completly reomoved from tests
box/sql.test, big.sql.test refactoring
sql.tests enabled in big and box suites
Replication tests sql refactoring
parallel call.test sql refactoring
box.error test fixed in call.test

After review fixes:
1. rename remote to iproto
2. remove old sql tests
3. update test-run

*) Splitted rlist initializer to RLIST_HEAD_INITIALIZER(..) and RTREE_LINK_INITIALIZER

*) Additionally added GT iterator
*) Added  test for that