Remove spurious NOTICE event addition to event list

I stumbled upon the situation, when I want to `react_on` NOTICE event. I wrote some code for a plugin and it
turned out, that the method, which "reacts on" the event was executing twice:

```
[2012/05/03 18:48:50.981] >> :Q!TheQBot@CServe.quakenet.org NOTICE Artaius_ :CHALLENGE 34f6f5232658b9facff0aadc3e37954b HMAC-MD5 HMAC-SHA-1 HMAC-SHA-256 LEGACY-MD5
[2012/05/03 18:48:50.982] !! [New thread] For #<Cinch::Handler @event=:notice pattern=#<Cinch::Pattern:0xa4a0970 @prefix=nil, @pattern=/^CHALLENGE (.+?) (.+)$/, @suffix=nil>>: #<Thread:0xa305908> -- 2 in total.
[2012/05/03 18:48:50.982] !! [Artaius::Plugins::Identify] Received challenge '34f6f5232658b9facff0aadc3e37954b'
[2012/05/03 18:48:50.983] !! [Thread done] For #<Cinch::Handler @event=:notice pattern=#<Cinch::Pattern:0xa4a0970 @prefix=nil, @pattern=/^CHALLENGE (.+?) (.+)$/, @suffix=nil>>: #<Thread:0xa305908> -- 1 remaining.
[2012/05/03 18:48:50.983] !! [New thread] For #<Cinch::Handler @event=:notice pattern=#<Cinch::Pattern:0xa4a0970 @prefix=nil, @pattern=/^CHALLENGE (.+?) (.+)$/, @suffix=nil>>: #<Thread:0xa305020> -- 2 in total.
[2012/05/03 18:48:50.983] !! [Artaius::Plugins::Identify] Received challenge '34f6f5232658b9facff0aadc3e37954b'
[2012/05/03 18:48:50.983] << PRIVMSG Q@CServe.quakenet.org :CHALLENGEAUTH artaius efce18a14b1b57ac79015e5da1f57da3d904e1fe17eedfe84a90a51ec9a813b6 HMAC-SHA-256
[2012/05/03 18:48:50.984] << PRIVMSG Q@CServe.quakenet.org :CHALLENGEAUTH artaius efce18a14b1b57ac79015e5da1f57da3d904e1fe17eedfe84a90a51ec9a813b6 HMAC-SHA-256
[2012/05/03 18:48:50.984] !! [Thread done] For #<Cinch::Handler @event=:notice pattern=#<Cinch::Pattern:0xa4a0970 @prefix=nil, @pattern=/^CHALLENGE (.+?) (.+)$/, @suffix=nil>>: #<Thread:0xa305020> -- 0 remaining.
[2012/05/03 18:48:52.991] >> :Q!TheQBot@CServe.quakenet.org NOTICE Artaius_ :You are now logged in as Artaius.
[2012/05/03 18:48:52.992] >> :Q!TheQBot@CServe.quakenet.org NOTICE Artaius_ :Remember: NO-ONE from QuakeNet will ever ask for your password.  NEVER send your password to ANYONE except Q@CServe.quakenet.org.
[2012/05/03 18:48:54.960] >> :Q!TheQBot@CServe.quakenet.org NOTICE Artaius_ :CHALLENGEAUTH is not available once you have authed
```

So, for every new NOTICE Cinch creates _two_ `:notice` events to be called by handlers.

The first addition is here: [https://github.com/cinchrb/cinch/blob/b73c62cbd3a54ef83121691e57368ba10da2cdf8/lib/cinch/irc.rb#L248][0]
And the second is here: [https://github.com/cinchrb/cinch/blob/b73c62cbd3a54ef83121691e57368ba10da2cdf8/lib/cinch/irc.rb#L263][1]

So, whenever it parses such a string as this…:

```
[2012/05/03 18:48:50.981] >> :Q!TheQBot@CServe.quakenet.org NOTICE Artaius_ :CHALLENGE 34f6f5232658b9facff0aadc3e37954b HMAC-MD5 HMAC-SHA-1 HMAC-SHA-256 LEGACY-MD5
```

…it molds the following `event` Array:

```ruby
events
# => [[:catchall], [:private], [:notice], [:notice]]
```

For example, for PRIVMSG it would look like this, which is OK:

```ruby
msg.command
# => "PRIVMSG"
events
# => [[:catchall], [:private], [:message], [:notice]]
```
 
In this pull request I tried to eliminate this duplication of "notices". Hard to say, whether I fucked up something or not, but at least you are aware of the bug now :)

[0]: https://github.com/cinchrb/cinch/blob/b73c62cbd3a54ef83121691e57368ba10da2cdf8/lib/cinch/irc.rb#L248
[1]: https://github.com/cinchrb/cinch/blob/b73c62cbd3a54ef83121691e57368ba10da2cdf8/lib/cinch/irc.rb#L263