sophia: submodule update (buildbot related)
implement sophia index drop.

closes #gh-238.
sophia index: fix for 'crash if insert without index'.

closes #gh-280.
fix gh-430 make clean kills ./src/uri.cc
Fix gh-431: sophia: assertion if box.begin.
Merge branch 'master' of github.com:mailru/tarantool
fix gh-404 gcc 4.9 warning
Add explicit box.rollback() in test for gh-431.
Merge remote-tracking branch 'origin/master' into fix-gh-194