Refactor Service::Start method.

This CL extracts code from Service::Start into four helper functions,
bringing Service::Start down to 134 lines vs 212 lines originally. This
makes the method a lot easier to follow. There is no change in behaviour.

Also, make error messages consistent (start with lowercase) and
format Service::Start to fit in 100 cols.

Bug: 30035168

Change-Id: If979976fba4d339a336d030f802ca9f169fd012c
diff --git a/init/service.h b/init/service.h
index 38c5d64..aa73aaf 100644
--- a/init/service.h
+++ b/init/service.h
@@ -113,6 +113,8 @@
     void OpenConsole() const;
     void PublishSocket(const std::string& name, int fd) const;
     void KillProcessGroup(int signal);
+    void CreateSockets(const std::string& scon);
+    void SetProcessAttributes();
 
     bool ParseClass(const std::vector<std::string>& args, std::string* err);
     bool ParseConsole(const std::vector<std::string>& args, std::string* err);