Create Bloom filters whenever waiting to do a merge.  Remove the 'lsm_bloom_newest' configuration, since this change makes it redundant.

refs #591
Merge branch 'develop' into lsm-bloom-newest
Merge branch 'develop' into lsm-bloom-newest
Fix error handling in backup cursor open.

Without this change test_backup03 hangs occasionally, with this change it
reports an error instead.
Always use the chunk flags to check for Bloom filter existence.  Sometimes chunk->bloom_uri is set before the Bloom filter has been populated.

refs #591
Fix a long-standing deadlock that could happen when closing a busy LSM tree.

The fix involves spinning on the schema lock and having LSM worker threads inherit the "schema locked" flag when they are shutting down.

refs #349
Merge branch 'develop' into lsm-bloom-newest

Conflicts:
	src/cursor/cur_stat.c
	src/include/schema.h
Merge pull request #591 from wiredtiger/lsm-bloom-newest

Automatically create bloom filters if merges stop. This branch also fixes some long standing races between LSM and schema level operations.