chore(utils): improve error message for incompatible ghost zip

refs TryGhost#681
refs TryGhost#587

Give the user more information why the installation of the zip file failed. Renders the required and the current installed CLI version and the command to run to solve the issue.

Author: aileen

lib/utils/version-from-zip.js

@@ -5,6 +5,7 @@ const errors = require('../errors');
 const semver = require('semver');
 const AdmZip = require('adm-zip');
 const cliPackage = require('../../package.json');
+const chalk = require('chalk');
 
 module.exports = function versionFromZip(zipPath, currentVersion) {
     if (!path.isAbsolute(zipPath)) {
@@ -40,7 +41,10 @@ module.exports = function versionFromZip(zipPath, currentVersion) {
     }
 
     if (pkg.engines && pkg.engines.cli && !semver.satisfies(cliPackage.version, pkg.engines.cli)) {
-        return Promise.reject(new errors.SystemError('Zip file contains a Ghost version incompatible with this version of the CLI.'));
+        return Promise.reject(new errors.SystemError({
+            message: 'Zip file contains a Ghost version incompatible with this version of the CLI.',
+            help: `Required: v${pkg.engines.cli}, current: v${cliPackage.version}\n\n      Please run ${chalk.green('sudo npm install -g ghost-cli@latest')} and try again.`
+        }));
     }
 
     if (currentVersion && semver.lt(pkg.version, currentVersion)) {

test/unit/utils/version-from-zip-spec.js

@@ -106,6 +106,7 @@ describe('Unit: Utils > versionFromZip', function () {
         }).catch((error) => {
             expect(error).to.be.an.instanceof(errors.SystemError);
             expect(error.message).to.equal('Zip file contains a Ghost version incompatible with this version of the CLI.');
+            expect(error.options.help).to.equal('Required: v^0.0.1, current: v1.7.0\n\n      Please run \u001b[32msudo npm install -g ghost-cli@latest\u001b[39m and try again.');
         });
     });