add 'FromFallback' IP address source.
If X-* header is available, use its value as source IP.
If not, use the peer address of the connection.
Merge pull request #16 from notogawa/master

add 'FromFallback' IP address source.
adding doctest to wai-logger.
New logging system for multicore IO manager of GHC 7.8.
deleting Date.

FIXME: We need to support Windows.
New logger system for multicore IO manager of GHC 7.8.
renaming modules.
fixing tests.
hiding unnecessary modules.
exporting FileLogSpec.
updating doc.
proper type.
doc update.
withStdoutLogger.
losing type.
withStdoutLogger flushes on termination.
doc update.
updating doc.
removing warning.
Supporting Windows.