Added contributing.md and improved README

CONTRIBUTING.md

+## Test262 Authoring Guidelines
+### Test Case Style
+A test file has the following style format:
+```javascript
+// Copyright (C) 2014 [Contributor Name]. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/* 
+ * Tags...
+ */
+ 
+[Test Code]
+```
+### Tags
+Test262 officially supports the following tags: **@description**, **@negative**, **@path** & **@author**
+##### @description
+This tag is used to describe the purpose of a particular testcase. 
+Eg: Insert <LS> between chunks of one string
+##### @negative [.] \(not supported by Python console harness)
+Negative means the test will throw an error and given the error there will be a string comparison on the error message. It has an optional second parameter (it's a *regex-dot* if not provided) that will be used to compare. For best practices on how to use negative tag please see Handling Errors and Negative Test Cases.
+##### @path
+This tag is used by the JSON packaging. It is not needed to manually enter this tag.  
+##### @author
+This tag is used to identify the author of a test case. It's optional.
+
+There are also couple other tags which are used only by the Python runner: **@onlyStrict**, **@noStrict**
+##### @onlyStrict
+Will run the test only in strict mode
+##### @noStrict
+Will not run the test in strict mode
+
+### Handling Errors and Negative Test Cases
+The following patterns are considered the best practice:
+#### Runtime Error:
+```javascript
+var error;
+
+try {
+    [test code]
+} catch (e) {
+    error = e;
+}
+
+if (error === undefined) {
+    $ERROR('expected to throw an error but no error was thrown');
+} else if(!(e instanceof ReferenceError)) {
+    $ERROR('expected to have ReferenceError, got ' + error.name + ' instead.');
+}
+```
+The example uses ReferenceError however it's also possible to use any of the following error here:
+
+- EvalError
+- RangeError
+- ReferenceError
+- TypeError
+- URIError
+
+#### Syntax Error & Early Error:
+```javascript
+/*
+ * @negative ^((?!NotEarlyError).)*$
+ */
+ 
+throw "NotEarlyError"; 
+[test code]
+```
+There are *very* few cases where a syntax error is **not** an early error. In those cases use the Runtime Error pattern but wrap the test code in an eval statement. Be careful, eval code is not global code!
+### Other Features
+#### $INCLUDE(fileName) method
+$INCLUDE (not supported by Python console harness) will load an external Javascript file in the same context before executing a test. In most cases usage of this method should be avoided. It's a good practice only when a large amount of tests need a special check that's not provided by the default harness. If that's the case, please explain the use case in detail.
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README.md

-Test262 is the official ECMAScript (ECMA-262) conformance suite.
+## Test262 is the official ECMAScript (ECMA-262) conformance suite.
 
-### Contributing to Test262 ###
+### Contributing to Test262
+> See contributing.md
 
 1. Sign the [Test262 CLA](http://tc39.github.io/test262-cla).
-2. Send a pull request.
+2. Send a pull request. Please make sure you have one commit per pull request. If you have multiple commits, squash them before sending the pull request.
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