fix #2066 mixpanel wordcount property

fix #2066 mixpanel wordcount property
If an accurate word count is important, then some other technique should be used since this will count image tags due to the use of Html.fromHtml(). For example, this is counted as four words instead of two:
```
One <img src="image.jpg" /> two <img src="image.jpg" />
```
This also doesn't take word boundaries other than spaces into account. Java's `BreakIterator` may be a better choice here.