Support non-integer primary key in shorthand function

Author: xenadu

SQLite Tests/SchemaTests.swift

@@ -7,6 +7,7 @@ private let age = Expression<Int?>("age")
 private let salary = Expression<Double>("salary")
 private let admin = Expression<Bool>("admin")
 private let manager_id = Expression<Int64?>("manager_id")
+private let uniqueIdentifier = Expression<UniqueIdentifier>("uniqueIdentifier")
 
 class SchemaTests: XCTestCase {
 
@@ -45,6 +46,18 @@ class SchemaTests: XCTestCase {
         )
     }
 
+    func test_createTable_column_nonIntegerPrimaryKey() {
+        ExpectExecution(db, "CREATE TABLE \"users\" (\"email\" TEXT PRIMARY KEY NOT NULL)",
+            db.create(table: users) { $0.column(email, primaryKey: true) }
+        )
+    }
+    
+    func test_createTable_column_customTypePrimaryKey() {
+        ExpectExecution(db, "CREATE TABLE \"users\" (\"uniqueIdentifier\" TEXT PRIMARY KEY NOT NULL)",
+            db.create(table: users) { $0.column(uniqueIdentifier, primaryKey: true) }
+        )
+    }
+
     func test_createTable_column_withPrimaryKey_buildsPrimaryKeyClause() {
         ExpectExecution(db, "CREATE TABLE \"users\" (\"id\" INTEGER PRIMARY KEY NOT NULL)",
             db.create(table: users) { t in

SQLite Tests/TestHelper.swift

@@ -55,3 +55,16 @@ func ExpectExecution(db: Database, SQL: String, statement: @autoclosure () -> St
 func ExpectExecution(db: Database, SQL: String, query: Query) {
     ExpectExecutions(db, [SQL: 1]) { _ in for _ in query {} }
 }
+
+
+public class UniqueIdentifier : NSUUID, Value {
+    public class var declaredDatatype:String { get { return "TEXT" } }
+    
+    public class func fromDatatypeValue(datatypeValue: String) -> UniqueIdentifier {
+        return UniqueIdentifier(UUIDString: datatypeValue)!
+    }
+    
+    public var datatypeValue: String {
+        return self.UUIDString
+    }
+}

SQLite/Schema.swift

@@ -193,12 +193,8 @@ public final class SchemaBuilder {
     ) {
         column(Expression<V>(name), nil, true, unique, check, value.map { Expression(value: $0) })
     }
-
-    // MARK: - INTEGER Columns
-
-    // MARK: PRIMARY KEY
-
-    public func column<V: Value where V.Datatype == Int64>(
+    
+    public func column<V: Value>(
         name: Expression<V>,
         primaryKey: Bool,
         unique: Bool = false,
@@ -207,6 +203,10 @@ public final class SchemaBuilder {
         column(name, primaryKey ? .Default : nil, false, unique, check, nil, nil)
     }
 
+    // MARK: - INTEGER Columns
+
+    // MARK: PRIMARY KEY
+
     public enum PrimaryKey {
 
         case Default