Add Core implementation

Add all core implementation for the library.

Author: Rafael da Silva Ferreira

JSONStub/Classes/FileStub.swift

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+//
+//  FileStub.swift
+//  Pods
+//
+//  Created by Rafael Ferreira on 10/25/16.
+//
+//
+
+public protocol FileStub {
+    var fileName: String { get }
+}

JSONStub/Classes/Mappable.swift

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+//
+//  Mappable.swift
+//  NuChargebackTests
+//
+//  Created by Rafael Ferreira on 10/5/16.
+//  Copyright © 2016 Swift Yah. All rights reserved.
+//
+
+import ObjectMapper
+
+public extension Mappable {
+    init?(fromFileName file: String) {
+        guard let json = file.fileDictionary() else { return nil }
+
+        self.init(JSON: json)
+    }
+
+    init?(fromStub stub: FileStub) {
+        self.init(fromFileName: stub.fileName)
+    }
+
+    var asData: Data {
+        guard let json = toJSONString(), let data = json.data(using: .utf8), json != "{}" else { return Data() }
+
+        return data
+    }
+}

JSONStub/Classes/ReplaceMe.swift

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+//
+//  String.swift
+//  NuChargeback
+//
+//  Created by Rafael Ferreira on 10/5/16.
+//  Copyright © 2016 Swift Yah. All rights reserved.
+//
+
+public extension String {
+    func fileData() -> Data? {
+        guard let path = filePath() else { return nil }
+
+        let url = URL(fileURLWithPath: path)
+
+        return try? Data(contentsOf: url)
+    }
+
+    func fileDictionary() -> [String: AnyObject]? {
+        guard let data = fileData(),
+            let json = try? JSONSerialization.jsonObject(with: data, options: .allowFragments) else { return nil }
+
+        return json as? [String: AnyObject]
+    }
+
+    func filePath() -> String? {
+        guard splitAtDot.count == 2 else { return nil }
+
+        return Bundle.main.path(forResource: splitAtDot.first, ofType: splitAtDot.last)
+    }
+}
+
+// MARK: Utility functions
+
+extension String {
+    var splitAtDot: [String] {
+        return splitBy(separator: ".")
+    }
+
+    func splitBy(separator: String) -> [String] {
+        guard let character = separator.characters.first else { return [self] }
+
+        return characters.split(separator: character).map({ String($0) })
+    }
+}
+
+// MARK: Case functions
+
+public extension String {
+    var pascalCase: String {
+        return first.uppercased() + last
+    }
+}
+
+// MARK: Private functions
+
+private extension String {
+    var first: String {
+        let item = characters.prefix(1)
+
+        return String(item)
+    }
+
+    var last: String {
+        let array = characters.dropFirst()
+
+        return String(array)
+    }
+}