Check for Ember version with new ember-cli-version-checker API.

[dan-ste]

Since ember introduced the ember-source from NPM, update API usage of ember-cli-version-checker.

[dan-ste]

For now, we have these errors during app build.

Invalid Version: undefined TypeError: Invalid Version: undefined at new SemVer (/Users/w/projects/lpserver/frontend/addons/lp-base/node_modules/ember-cli-version-checker/node_modules/semver/semver.js:281:11) at compare (/Users/w/projects/lpserver/frontend/addons/lp-base/node_modules/ember-cli-version-checker/node_modules/semver/semver.js:571:10) at Function.lt (/Users/w/projects/lpserver/frontend/addons/lp-base/node_modules/ember-cli-version-checker/node_modules/semver/semver.js:605:10) at BowerDependencyVersionChecker.DependencyVersionChecker.(anonymous function) [as lt] (/Users/w/projects/lpserver/frontend/addons/lp-base/node_modules/ember-cli-version-checker/index.js:68:26) at Class.treeForAddonTemplates (/Users/w/projects/lpserver/frontend/addons/lp-base/node_modules/ember-modal-dialog/index.js:29:13) at Class._treeFor (/Users/w/projects/lpserver/frontend/addons/lp-base/node_modules/ember-cli/lib/models/addon.js:517:33) at Class.addonTemplateFiles [as _addonTemplateFiles] (/Users/w/projects/lpserver/frontend/addons/lp-base/node_modules/ember-cli/lib/models/addon.js:898:31) at Class.compileTemplates (/Users/w/projects/lpserver/frontend/addons/lp-base/node_modules/ember-cli/lib/models/addon.js:949:81) at Class.compileAddon (/Users/w/projects/lpserver/frontend/addons/lp-base/node_modules/ember-cli/lib/models/addon.js:1008:30) at Class.treeForAddon (/Users/w/projects/lpserver/frontend/addons/lp-base/node_modules/ember-cli/lib/models/addon.js:661:26)

[andrewhavens]

Thanks for the PR @dan-ste!