Changes to stats output

Truncate file when logshifter starts, instead of before writing each
stats interval.

Output JSON instead of multiple lines per interval.
Merge pull request #3 from ncdc/append-stats

Changes to stats output
Fix some buffering issues
Merge pull request #5 from ironcladlou/buffering-fixes

Fix some buffering issues
TravisCI integration
Added readme
Instruct travis to use go 1.2
Update README
Merge pull request #6 from ironcladlou/docs

Update README
Stats changes

Set defaults for most config options.
Only capture stats if enabled in config file.
Separate stat collection from reporting

Make stat collection itself orthogonal to reporting of stats so tests
can inspect stats without relying on report timing.
Merge pull request #8 from ironcladlou/stats-only-when-enabled

Stats refactoring
Refactor stats handling
Merge pull request #9 from ironcladlou/stats-refactor

Refactor stats handling
Simplify WaitGroup handling
Merge pull request #10 from ironcladlou/async-refactor

Simplify WaitGroup handling
Implement file output writer

Also fix config bug which caused queuesize and inputbuffersize to
be ignored.
Merge pull request #11 from ironcladlou/file-output

Implement file output writer
Remove debugging line
Fix imports