added per-thread lock wait timeout for sharding #1168

not exposed as user command yet, but probably should
added user command to set lock timeout #1168
added NEWS about #1168
added test for per-client lock wait timeout #1168
Merge pull request #1169 from Tokutek/migrate-lock-timeout

added per-thread lock wait timeout

fixes #1168
Merge branch 'bugfixes/tokumx-1.5'