Conform Bool to Content (#2848)

* Add bool to support content protocol by default

Add bool to support the content protocol by default. You can directly return bool types at the top level.

````swift
    app.get("isOK") { req in
        return true
    }
``

* New test bool supports content protocol

Co-authored-by: king <3925@winnermedical.com>

Sources/Vapor/Content/Content.swift

@@ -111,6 +111,8 @@ extension UInt16: Content { }
 extension UInt32: Content { }
 extension UInt64: Content { }
 
+extension Bool: Content {}
+
 extension BinaryFloatingPoint where Self: Content {
     public static var defaultContentType: HTTPMediaType {
         return .plainText

Tests/VaporTests/ContentTests.swift

@@ -489,6 +489,19 @@ final class ContentTests: XCTestCase {
             XCTAssertEqual(res.status, .badRequest)
         }
     }
+
+    func testContentIsBool() throws {
+        let app = Application(.testing)
+        defer { app.shutdown() }
+
+        app.routes.get("success") { req in
+            return true
+        }
+
+        try app.testable().test(.GET, "/success") { res in
+            XCTAssertEqual(try res.content.decode(Bool.self), true)
+        }
+    }
 }
 
 private struct SampleContent: Content {