Fixes #114

Avoid doing a 500 if query can't be converted to a CONSTRUCT (for exampe, when using aggregation functions)

Also, now variable.value == variable.curie if it is a literal

Added sparql filter module that allow users to filter by a random query rather than a type to select a model/view for a URI

Page will be processed by Haanga

Fix bug that when not specified prefixes and converting query from SELECT to DESCRIBE, lodspk returns a 500

Solves #106

For example

```
{% for i in models.main%}
Language tag of "{{i.variable.value}}" is "{{i.variable.lang}}"
Datatype of "{{i.variable.value" is "{{i.variable.type}}"
{%endfor%}
```

This solves #105

Adding user agent LODSPeaKr

Fixing adding triples when external URI was off

Fixing bug with Contenttype returned

Adding named graph on default service

among other bugs