Support '-suppress warnings'

#KT-3319 In Progress

compiler/testData/cli/help.out

@@ -13,9 +13,10 @@ Usage: org.jetbrains.jet.cli.jvm.K2JVMCompilerArguments
   -output [String] output directory
   -module [String] module to compile
   -script [flag] evaluate script
+  -kotlinHome [String] Path to Kotlin compiler home directory, used for annotations and runtime libraries discovery
   -tags [flag] Demarcate each compilation message (error, warning, etc) with an open and close tag
   -verbose [flag] Enable verbose logging output
   -version [flag] Display compiler version
-  -help (-h) [flag] show help
-  -kotlinHome [String] Path to Kotlin compiler home directory, used for annotations and runtime libraries discovery
+  -help (-h) [flag] Show help
+  -suppress [String] Suppress compiler messages by severity (warnings)
 OK

compiler/testData/cli/suppressAllWarningsJS.out

@@ -0,0 +1 @@
+OK

compiler/testData/cli/suppressAllWarningsLowercase.out

@@ -0,0 +1 @@
+OK

compiler/testData/cli/suppressAllWarningsMixedCase.out

@@ -0,0 +1 @@
+OK

compiler/testData/cli/warnings.kt

@@ -0,0 +1,10 @@
+import jet.Any
+import jet.Any
+
+fun foo(p: Int??) {
+
+}
+
+trait T {
+    abstract fun foo()
+}

compiler/testData/cli/wrongArgument.out

@@ -14,9 +14,10 @@ Usage: org.jetbrains.jet.cli.jvm.K2JVMCompilerArguments
   -output [String] output directory
   -module [String] module to compile
   -script [flag] evaluate script
+  -kotlinHome [String] Path to Kotlin compiler home directory, used for annotations and runtime libraries discovery
   -tags [flag] Demarcate each compilation message (error, warning, etc) with an open and close tag
   -verbose [flag] Enable verbose logging output
   -version [flag] Display compiler version
-  -help (-h) [flag] show help
-  -kotlinHome [String] Path to Kotlin compiler home directory, used for annotations and runtime libraries discovery
+  -help (-h) [flag] Show help
+  -suppress [String] Suppress compiler messages by severity (warnings)
 INTERNAL_ERROR