added more S3 convenience functions based upon URIs
added ability to bypass GCLock when we know that a structure is immutable
update the default behaviour for when no metrics logger is defined in the config. Now it doesn't print anything.
started separating off signing logic from aws
use std::isnan explicitly to disambiguate with other declarations
fixed some compilation issues with gcc 4.7
fixed future handling for gcc 4.6
actually using the compatiblity layer for future::wait_for
Merge pull request #24 from dohse/fix-empty-field-handling

Fix empty field handling
added ability to perform Amazon v4 signatures and basic SQS service
Merge branch 'master' of github.com:datacratic/soa

Conflicts:
	gc/gc_lock.h
added missing commit from last merge
refactoring of AWS code to move more generic code and tests into soa
deal with strange extra newline at end of base64 digest
more sqs functionality
added set<> value description
remove debugging accidentally left in
fixed URL encoding in AWS service base
turned off debugging in AWS base
partially implemented SqsApi::deleteMessage (untested)