More brief somaxconn logging

- Consistent log message format
- Avoid unnecessary autoboxing when debug level is off
- Remove the duplication of somaxconn path
Clean-up d9cccccbb3344997e016e6a3603126ce65705c4d

- Revert irrelevant formatting changes
- Rename resource files
  - Add .pem
  - Remove 'netty' from names
Add more utility methods to check the availability of the epoll transport

Related issue: #2733

Motivation:

Unlike OpenSsl, Epoll lacks a couple useful availability checker
methods:

- ensureAvailability()
- unavailabilityCause()

Modifications:

Add missing methods

Result:

More ways to check the availability and to get the cause of
unavailability programatically.
[#2732] HttpRequestEncoder may produce invalid uri if uri parameters are included.

Motivation:

If the requests contains uri parameters but not path the HttpRequestEncoder does produce an invalid uri while try to add the missing path.

Modifications:

Correctly handle the case of uri with paramaters but no path.

Result:

HttpRequestEncoder produce correct uri in all cases.
Port ChannelOutboundBuffer and related changes from 4.0

Motivation:

We did various changes related to the ChannelOutboundBuffer in 4.0 branch. This commit port all of them over and so make sure our branches are synced in terms of these changes.

Related to [#2734], [#2709], [#2729], [#2710] and [#2693] .

Modification:
Port all changes that was done on the ChannelOutboundBuffer.

This includes the port of the following commits:
 - 73dfd7c01b49aca006a34cc48197dee3fc360af1
 - 997d8c32d23f2d88903b7b607360907b99101002
 - e282e504f17b0874719ff606c728494e3509b1a0
 - 5e5d1a58fd3159c04ac7d10edfb8ed7a83d3935e
 - 8ee3575e72d6ee000a99c717d96f36695a8667a0
 - d6f0d12a8692c095df43b2a4462cbc97cf5c5a2d
 - 16e50765d1fb99005ad761409c28dcedf477531b
 - 3f3e66c31ae3da70c36cc125ca9bcac8215390e4

Result:
 - Less memory usage by ChannelOutboundBuffer
 - Same code as in 4.0 branch
 - Make it possible to use ChannelOutboundBuffer with Channel implementation that not extends AbstractChannel
Make channelRead final in SimpleChannelInboundHandler.

Motivation:

Users might override channelRead by accident.
See http://stackoverflow.com/questions/25110538/netty-ping-pong-with-a-pojo

Modifications:

Make channelRead final.

Result:

Can't override channelRead.