chore(ionicons): remove the import of ionicons css

[brandyscarney]

Short description of what this resolves:

Importing the ionicons.scss file from ionicons was adding css that is not desired. Specifically, the .ion class here: https://github.com/driftyco/ionicons/blob/3.0/dist/scss/ionicons.scss#L29-L41

The .ion class itself isn't added to our icons, but it is extended here: https://github.com/driftyco/ionicons/blob/3.0/dist/scss/ionicons-common.scss#L941

So because of this extend, each icon class was getting this css which caused issues all over the e2e tests and in Ionic apps as well. The rule that is causing the issues is line-height: 1.

For example:

Changes proposed in this pull request:

• Remove node_modules/ionicons/dist/scss from the sass config so that it won't import ionicons.scss from there and instead will import it from src/fonts/
• Change the import for ionicons-icons and ionicons-variables to include the full path with node_modules, because without ionicons in the includePaths it will throw errors that it can't find it

Ionic Version: 2.x

[brandyscarney]

Closing this, we went a different route instead where we just added a new file with a different name to import from: https://github.com/driftyco/ionic/blob/master/src/themes/ionic.ionicons.scss

Starters, preview app and conference app will need to be updated to import from ionic.ionicons here: https://github.com/driftyco/ionic-conference-app/blob/master/src/theme/variables.scss#L81