Additional API support

[avargaskun]

Adding the following functionality to the plugin:

• Support for creating ZIP files in IOS
• Support for creating ZIP files from multiple input source files
• Running plugin logic asynchronously

This makes breaking changes to the API (see further below for examples):

• zip method removed
• New zipFolder method to create ZIP from single folder (similar to previous zip method)
  • Removed options parameter, replaced with parameter containing target zip file
• New zipFiles method to create ZIP from one or more files
• Removed options parameter from unzip method, replaced with parameter containing target folder

Examples:

// Creating ZIP from single folder
window.JJzip.zipFolder(
    cordova.file.dataDirectory + 'inputFolder',
    cordova.file.dataDirectory + 'out.zip',
    function() { console.log('success'); },
    function(err) { console.log('error: ' + err) });

// Creating ZIP with multiple files
const files = [
    cordova.file.dataDirectory + 'file1.txt',
    cordova.file.dataDirectory + 'file2.txt',
];
window.JJzip.zipFiles(
    files,
    cordova.file.dataDirectory + 'out.zip',
    function() { console.log('success'); },
    function(err) { console.log('error: ' + err) });

// Unzipping into target folder
window.JJzip.unzip(
    cordova.file.dataDirectory + 'input.zip',
    cordova.file.dataDirectory + 'extracted',
    function() { console.log('success'); },
    function(err) { console.log('error: ' + err) });

[avargaskun]

Hello! Thank you for this writing this helpful plug-in. Here's a few improvements a while back in case you're interested in pulling them into the main branch. This includes a breaking change to the plug-in API so I bumped the version number (2.0.0 -> 3.0.0)