new: custom bundle build dir basenames w/ parseBundle() option

Allow bundle build directory naming to be specified by a function
passed as a parameter to parseBundle via option object key named
"buildDirectoryNamer". The function is passed the bundle object
(see lib/bundle.js).

i.e.

    var loc = new Locator({buildDirectory: 'build'}),
        opts = {buildDirectoryNamer: function(bundle) {
                return bundle.name + '_' + bundle.version;
            }};

    loc.parseBundle(__dirname, opts).then(/* ... */);
minor: rm/update outdated api doc info, whsp, in _makeBundle()
incorporate naming and comment change feedback

- rename buildDirectoryNamer option to bundleBuildDirectoryParser
- rename _nameBuildDirectory parameter basedir to buildDirectory
- improve api doc comments for _nameBuildDirectory
set this._options.bundleBuildDirectoryParser conditionally

This option property may be applied in the constructor and/or
parseBundle().
+option property api docs for BundleLocator(), parseBundle()
Merge pull request #11 from isao/build_dir_namer

custom bundle build dirnames w/constructor and/or parseBundle() option

Allow bundle build directory naming to be specified by a function
passed as a parameter to parseBundle via option object key named
"buildDirectoryNamer". The function is passed the bundle object
(see lib/bundle.js).

i.e.
    var locator = new Locator({buildDirectory: 'build'}),
        opts = {bundleBuildDirectoryParser: function(bundle) {
                return bundle.name + '_' + bundle.version;
            }};

    locator.parseBundle(__dirname, opts).then(/* ... */);