Use FINE instead of TRACE when fine logging

It turns out TRACE is a higher logging level than DEBUG which doesn't
make much sense and is confusing. We can use FINE to achieve the same
thing and it's descriptive and less confusing
Remove some nonsense
Make the raft logging configurable
Set the node's connection string when creating a new raft server
Update the changelog for #1085
Don't try to take 2 snapshots at a time

Fix #943. Close #1081
Rename some constants

(from_clause.go,query.yacc,query_types.h): FROM_INNER_JOIN -> FROM_JOIN
Support joining multiple series using regex or list
don't enable raft debug log by default
Add some docs
Update docs for OS X.
Merge remote-tracking branch 'refs/remotes/origin/pr/973'
Don't write points if they are too old

Background of the bug: Prior to this patch we actually tried writing
points that were older than the retention period of the shard. This
caused race condition when it came to writing points to a shard that's
being dropped, which will happen frequently if the user is loading old
data (by accident). This is demonstrated in the test in this commit.This
bug was previously addressed in #985. It turns the fix for #985 wasn't
enough. A user reported in #1078 that some shards are left behind and
not deleted.

It turns out that while the shard is being dropped more write
requests could come in and end up on line `cluster/shard.go:195` which
will cause the datastore to create a shard on disk that isn't tracked
anywhere in the metadata. This shard will live forever and never get
deleted. This fix address this issue by not writing old points in, but
there are still some edge cases with the current implementation, at
least not as bad as current master.

Close #1078
Fix #1024: cleanup files if shard creation fails