Moving ObjC specific clang-format rules to the common config

Summary: I found that clang-format config file allows to specify rules on a per-language basis, so I moved Objective-C specific rules to the unified config. Now we have only one clang-format file. Yay!

Reviewed By: JoshuaGross

Differential Revision: D14018902

fbshipit-source-id: 45c1e185b8f2b8151ea202b3d9a68a3886597198

.clang-format

@@ -60,8 +60,8 @@ MacroBlockEnd:   ''
 MaxEmptyLinesToKeep: 1
 NamespaceIndentation: None
 ObjCBlockIndentWidth: 2
-ObjCSpaceAfterProperty: false
-ObjCSpaceBeforeProtocolList: false
+ObjCSpaceAfterProperty: true
+ObjCSpaceBeforeProtocolList: true
 PenaltyBreakBeforeFirstCallParameter: 1
 PenaltyBreakComment: 300
 PenaltyBreakFirstLessLess: 120
@@ -84,4 +84,8 @@ SpacesInSquareBrackets: false
 Standard:        Cpp11
 TabWidth:        8
 UseTab:          Never
+---
+Language: ObjC
+ColumnLimit:     120
+BreakBeforeBraces: WebKit
 ...