Add the memory swappiness tuning option to docker.

Memory swappiness option takes 0-100, and helps to tune swappiness
behavior per container.
For example, When a lower value of swappiness is chosen
the container will see minimum major faults. When no value is
specified for memory-swappiness in docker UI, it is inherited from
parent cgroup. (generally 60 unless it is changed).

Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>

sysinfo/sysinfo.go

@@ -13,9 +13,10 @@ type SysInfo struct {
 }
 
 type cgroupMemInfo struct {
-	MemoryLimit    bool
-	SwapLimit      bool
-	OomKillDisable bool
+	MemoryLimit      bool
+	SwapLimit        bool
+	OomKillDisable   bool
+	MemorySwappiness bool
 }
 
 type cgroupCpuInfo struct {