Add fs.makedir() and fs.rename() APIs

[gruehle]

Add two new functions to brackets.fs:

makedir()

/**
 * Create a new directory.
 *
 * @param {string} path The path of the directory to create.
 * @param {number} mode The permissions for the directory, in numeric format (ie 0777)
 * @param {function(err)} callback Asynchronous callback function. The callback gets one argument.
 *
 * @return None. This is an asynchronous call that sends all return information to the callback.
 **/
function makedir(path, mode, callback);

NOTE
The mode parameter of makedir() is ignored for now. The directory is created with the full
permissions available to the current user.

rename()

/**
 * Rename a file or directory.
 *
 * @param {string} oldPath The old name of the file or directory.
 * @param {string} newPath The new name of the file or directory.
 * @param {function(err)} callback Asynchronous callback function. The callback gets one argument.
 *
 * @return None. This is an asynchronous call that sends all return information to the callback.
 **/
function rename(oldPath, newPath, callback);

BONUS FEATURES
This pull request also includes two small bonus features on the mac:

• The main window size and position is now remembered when quitting and relaunching Brackets. This change will also fix the issues on the Mac where some of the UI is not shown if the initial window size is too small (Display error on MacBook Pro (13") brackets#1689)
• The file dialogs are now modal sheets instead of modal dialogs.

[redmunds]

I am getting a build error on Mac OS X v10.6 due to the NSFileWriteFileExistsError flag is only available on OS X v10.7 and later.

[gruehle]

Thanks for reviewing!

Are you using XCode 4.x? XCode 3.2.6 is no longer supported.

I don't have a 10.6 system with me for testing, but this should be fine when running on a 10.6 system. If you try to rename an item to a name of an existing item, you will get a less friendly error message, but everything should work fine.

[jasonsanjose]

I'll take on the mac side of the review.

[redmunds]

Windows looks good. Re-assigning to @jasonsanjose to take a look at Mac (since I need to upgrade to Xcode 4).

[jasonsanjose]

Filed adobe/brackets#1759

[jasonsanjose]

Looks good. Merging