Improve apache_error format
Merge pull request #412 from y-ken/parser_apache_error

Improve apache_error format
Implement 'disable_retry_limit' output option.

Setting 'disable_retry_limit' causes 'retry_limit' to be ignored
in favor of retrying forever.  This implicitly disables any
secondary output configuration as well.
Merge pull request #415 from salty-g/master

Implement 'disable_retry_limit' output option.
Refactoring of SetTagKeyMixin and SetTimeKeyMixin.
Merge pull request #411 from baschtl/better-configurable-time-key-and-tag-key-mixins

Refactor time key and tag key mixins
v0.10.53
Update Cool.io dependency to 1.2. fixes #419
Merge pull request #420 from fluent/update-cool.io-to-1.2

Update Cool.io dependency to 1.2. fixes #419
Update msgpack dependency to 0.5
Merge pull request #421 from fluent/update-msgpack-to-0.5

Update msgpack dependency to 0.5
Forget to add blocking_timeout to in_stream. refs #419
Remove older rubygems support
Use v1 configuration by default
Unify License term