Log Message:
Update ruby-puma to 2.15.3.

=== 2.15.3 / 2015-11-07

* 1 bug fix:

  * Fix JRuby parser

=== 2.15.2 / 2015-11-06

* 2 bug fixes:
  * ext/puma_http11: handle duplicate headers as per RFC
  * Only set ctx.ca iff there is a params['ca'] to set with.

* 2 PRs merged:
  * Merge pull request #818 from unleashed/support-duplicate-headers
  * Merge pull request #819 from VictorLowther/fix-ca-and-verify_null-exception

=== 2.15.1 / 2015-11-06

* 1 bug fix:

  * Allow older openssl versions

=== 2.15.0 / 2015-11-06

* 6 minor features:
  * Allow setting ca without setting a verify mode
  * Make jungle for init.d support rbenv
  * Use SSL_CTX_use_certificate_chain_file for full chain
  * cluster: add worker_boot_timeout option
  * configuration: allow empty tags to mean no tag desired
  * puma/cli: support specifying STD{OUT,ERR} redirections and append mode

* 5 bug fixes:
  * Disable SSL Compression
  * Fix bug setting worker_directory when using a symlink directory
  * Fix error message in DSL that was slightly inaccurate
  * Pumactl: set correct process name. Fixes #563
  * thread_pool: fix race condition when shutting down workers

* 10 doc fixes:
  * Add before_fork explanation in Readme.md
  * Correct spelling in DEPLOYMENT.md
  * Correct spelling in docs/nginx.md
  * Fix spelling errors.
  * Fix typo in deployment description
  * Fix typos (it's -> its) in events.rb and server.rb
  * fixing for typo mentioned in #803
  * Spelling correction for README
  * thread_pool: fix typos in comment
  * More explicit docs for worker_timeout

* 18 PRs merged:
  * Merge pull request #768 from nathansamson/patch-1
  * Merge pull request #773 from rossta/spelling_corrections
  * Merge pull request #774 from snow/master
  * Merge pull request #781 from sunsations/fix-typo
  * Merge pull request #791 from unleashed/allow_empty_tags
  * Merge pull request #793 from robdimarco/fix-working-directory-symlink-bug
  * Merge pull request #794 from peterkeen/patch-1
  * Merge pull request #795 from unleashed/redirects-from-cmdline
  * Merge pull request #796 from cschneid/fix_dsl_message
  * Merge pull request #799 from annafw/master
  * Merge pull request #800 from liamseanbrady/fix_typo
  * Merge pull request #801 from scottjg/ssl-chain-file
  * Merge pull request #802 from scottjg/ssl-crimes
  * Merge pull request #804 from burningTyger/patch-2
  * Merge pull request #809 from unleashed/threadpool-fix-race-in-shutdown
  * Merge pull request #810 from vlmonk/fix-pumactl-restart-bug
  * Merge pull request #814 from schneems/schneems/worker_timeout-docs
  * Merge pull request #817 from unleashed/worker-boot-timeout