AC_Sprayer: standardize inclusion of libaries headers

This commit changes the way libraries headers are included in source files:

 - If the header is in the same directory the source belongs to, so the
 notation '#include ""' is used with the path relative to the directory
 containing the source.

 - If the header is outside the directory containing the source, then we use
 the notation '#include <>' with the path relative to libraries folder.

Some of the advantages of such approach:

 - Only one search path for libraries headers.

 - OSs like Windows may have a better lookup time.

libraries/AC_Sprayer/AC_Sprayer.cpp

@@ -1,7 +1,7 @@
 // -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
 
-#include <AP_HAL.h>
-#include <AC_Sprayer.h>
+#include <AP_HAL/AP_HAL.h>
+#include "AC_Sprayer.h"
 
 extern const AP_HAL::HAL& hal;
 

libraries/AC_Sprayer/AC_Sprayer.h

@@ -21,11 +21,11 @@
 #define AC_SPRAYER_H
 
 #include <inttypes.h>
-#include <AP_Common.h>
-#include <AP_Param.h>
-#include <AP_Math.h>
-#include <RC_Channel.h>
-#include <AP_InertialNav.h>     // Inertial Navigation library
+#include <AP_Common/AP_Common.h>
+#include <AP_Param/AP_Param.h>
+#include <AP_Math/AP_Math.h>
+#include <RC_Channel/RC_Channel.h>
+#include <AP_InertialNav/AP_InertialNav.h>     // Inertial Navigation library
 
 #define AC_SPRAYER_DEFAULT_PUMP_RATE        10.0f   // default quantity of spray per meter travelled
 #define AC_SPRAYER_DEFAULT_PUMP_MIN         0       // default minimum pump speed expressed as a percentage from 0 to 100