syntax: gotexttmpl identifier and string highlighting broken

[moorereason]

Actual behavior

Given the following Go HTML template:

{{ if eq .Site.Data.Level "premier" }}
<p class="special">
{{ end }}

Two issues arise:

1. .Site.Data.Level is not highlighted as an Identifier
2. The string " }}\n<p class=" is highlighted as a string. The first " on the first line is ignored.

Expected behavior

1. I expect .Site.Data.Level to be highlighted as an Identifier.
2. I expect "premier" to be highlighted as a String.

Steps to reproduce:

1. Create an HTML template with the above content.
2. Enable syntax highlighting.

Configuration

• nvim 0.1.3-dev (from ubuntu PPA)
• vim-go commit fc682ce

Fix

I'll submit a PR shortly with a proposed fix.