Add `NaN` support back in to collectd codec

* Add spec tests for NaN support
* Catch warning on NaN with nan_handling set to warn
* Make lambdas ivars and initialize so they can reference other ivars
* Fixed reference to point to ivar
* Streamline ivar declarations in one method
* Improve tests to cover more cases
* Make lambdas not be ivars
* Change idiomatic calling of init_lambdas to reflect lack of return value

closes 1363
Don't install development gems.

For whatever reason, the 'development' group is installed by default via
bundler. This was not intentiona.

The effect is that we might be unintentionally violating a dependency's
license (term-ansicolor is GPL2) by including it in our release.
Definitely do not wish such things.

With this patch, the next run of `bin/logstash deps` shows all dev
dependencies being removed:

    Removing coveralls (0.7.0)
    Removing docile (1.1.3)
    Removing kramdown (1.3.3)
    Removing rest-client (1.6.7)
    Removing simplecov (0.8.2)
    Removing simplecov-html (0.8.0)
    Removing term-ansicolor (1.3.0)
    Removing thor (0.18.1)
    Removing tins (1.0.0)

Fixes #1372
Merge pull request #1375 from jordansissel/fix/github-1372

Don't install development gems.
Disable coverage for now

This is to make tests run. Currently we are not using coverage reports,
and a recent fix to remove development dependencies from the normal
installation has caused coverage dependencies to be removed and thus
fail.

We will revert this once we figure out how to make tests run with
separate bundler groups.
Merge pull request #1376 from jordansissel/fix/test-failure-due-to-coverage-missing

Disable coverage for now
Fixing relative path issues left over from flatjar era

Use plugin_path and pattern_path

closes 1377
Automatically choose most correct codec for bytestream inputs.

Now, if you try to use `plain` or `json` codecs with either `stdin` or
`tcp` inputs, it will automatically select `line` or `json_lines` codec
respectively.

Right now, many users try to use json codec with tcp input. This
*should* work, but due to technical limitations[1], it does not.
To compensate, we have always provided a json_lines codec to help
parse "streams of line-delimited json" which is what most folks
seem to be handling these days.

[1] I haven't found a JSON library capable of processing a byte stream.
Jackson has one, but it requires an input stream model which logstash
does not currently expose. Future work will make this possible.

Related: #1391
fix stdin message handling & specs

closes #1386
Pass correct HOME env into chroot

Without this patch the logstash isn't able to start on Debian 7 when using file input, as both HOME and SINCEDB_DIR aren't set in chroot.
Merge branch 'pr/1343'
closes #1343
initial spec for pipe input

removed logging

fixed encoding header

closes 1385
replace json parsers with JrJackson and Oj
refactored timestamps with new Timestamp class
closes #1434
fix external command invocation
changelog for 1.4.2
Fix missing require
Fix typo
Fix for #1451

Line codec was using an undefined variable which casued it to throw and exception.

Fixed and added tests for line codes

Closes #1451
Squash extra lines
Verify method is getting called
Reference github issues now.

Hosted Jira (logstash.jira.com) is currently busted because we have
exceeded the maximum number of users that platform can accomodate
(according to Atlassian support). Until that is resolved, let's point
everyone at github issues instead.

closes #1508