Updated build.sh to extract current Git branch,commit and if any local files have been changed, these values are then used in the server startup message to make it clear what release of sync_gateway is being run. fixes issue #382
ignore local updates to git_info.go as this is done on every build
Filtered out ...origin in short form of git status
remove git_info.go from tracking so that local build updates are not committed
Modified unofficial HTTP Header string to match requirement
Removed debug line from build.sh and updated version string to extract build number from production builds if provided and reformat header output string
Merge branch 'master' of https://github.com/couchbase/sync_gateway into feature/issue_382

Conflicts:
	src/github.com/couchbaselabs/sync_gateway/rest/api.go
Merge pull request #397 from couchbase/feature/issue_382

Updated build.sh to extract current Git branch,commit