Start and stop eviction worker threads based on demand.

Refs #1116
Fix an off by one in dynamic eviction threads.
Add nvd3 wtperf example to doc. #1147
Minor edits to wtperf doc page.
Merge branch 'develop' into dynamic-evict-workers

Conflicts:
	src/btree/bt_evict.c
	src/conn/conn_cache.c
	src/include/cache.h
Merge branch 'develop' into wtperf-doc
Move performance into its own section. #1147
Change to update-large-lsm run. #1147
Don't have eviction workers close sessions.
Merge branch 'develop' into dynamic-evict-workers
Lint
Remove tcbench, it makes clang's static analyzer unhappy and we're not
doing to fix it.
Remove tcbench, it makes clang's static analyzer unhappy and we're not
doing to fix it.
Add new chart and performance.dox.
minor review/wordsmithing.
update
Add large-lsm config and use that for wtperf doc.
Merge branch 'wtperf-doc' of github.com:wiredtiger/wiredtiger into wtperf-doc

Conflicts:
	src/docs/wtperf.dox
Fix inconsistent home dir naming.
Add descriptions of wtperf args and script options.