First big commit that merges 0event into VAST.
More integration work & switch to 0event logger.
Import LZ4.
Remove more 0event vestiges.
Add missing forwarding function.
Fix link error due to missing ctor definition.
Migration of unit tests and to_string polishing.
Remove redundant declaration.
Add 0event unit tests.
Fix subtle filesystem bug.
Cleanup filesystem code a bit.
Resolve conflicting fixture name.
Migrate Travis configuration.
Merge branch 'topic/ze-migration'

* topic/ze-migration: (158 commits)
  Migrate Travis configuration.
  Resolve conflicting fixture name.
  Cleanup filesystem code a bit.
  Fix subtle filesystem bug.
  Add 0event unit tests.
  Remove redundant declaration.
  Migration of unit tests and to_string polishing.
  Fix link error due to missing ctor definition.
  Add missing forwarding function.
  Remove more 0event vestiges.
  Import LZ4.
  More integration work & switch to 0event logger.
  First big commit that merges 0event into VAST.
  Perform some maintainance.
  Fix segmentizer compilation.
  Replace "shutdown" with "kill" atom.
  Restructure and simplify ingestion process.
  Tweak cosmetics of asynchronous source mixin.
  Cleanup vast::source and vast::sink namespaces.
  Improve signal handling and remove policy.
  ...