nb-info icon not displayed in v. 1.1.0

### Issue type

**I'm submitting a ...** (check one with "x")

* [X] bug report
* [ ] feature request

### Issue description

**Current behavior:**

`nb-info` icon is not displayed. `` only renders a white space

When testing another icon (e.g. ``) it is correctly displayed

**Expected behavior:**

The icon should be displayed

**Steps to reproduce:**

With the latest version of both nebular theme (2.0.1) and nebular icon (1.1.0), try to display `nb-info`.

**Angular, Nebular**

"@nebular/bootstrap": "^2.0.1",
"@nebular/theme": "^2.0.1",
"nebular-icons": "^1.1.0",