Add more GZIP compressable MIME types

[RehanSaeed]

I raised the following PR aspnet/BasicMiddleware#181 (comment). This is a justifications for each MIME type to be added:

• application/rss+xml, application/atom+xml and image/svg+xml These are all just special dialects of XML, they are all web related and are fairly common (especially SVG).
• application/vnd.ms-fontobject, application/x-font-ttf, font/otf - TrueType fonts (ttf) and OpenType fonts (otf) can be safely be compressed for smaller size. The answer is unclear when it comes to Embedded OpenType (eot) fonts. It’s possible to compress EOT font files as part of the file creation process, in which case gzipping them is unnecessary. However, to generate compressed EOT font files requires a special tool and an extra step, so it’s likely that most of them are not pre-compressed. However, Google recommends compressing EOT fonts.
• image/x-icon - Finding references for this is more difficult and I can only provide my own anecdotal evidence and the fact that the HTML 5 Boilerplate Server Configs project also includes it for NGINX and IIS.

I only added the most used MIME types, this list could double in size if you wanted to support all web formats.

[Tratcher]

@glennc

[glennc]

Adding to 2.0 to prototype API changes for adding/removing mimetypes then re-evaluating this based on easier usage instead of modifying defaults.

[muratg]

@glennc Do you have any prototype API surface that you'd like to make adding/removing mimetypes easy?

[glennc]

I did have, but that was a long time ago. Let me go see.

[glennc]

At this point I don't think we will get to this one in 2.0. Moving to the punt bucket, if there is time we can look at it. But more likely it will slip to a later release.

[muratg]

@glennc move the milestone as well?

[muratg]

Triage:

1. Verify if the extensibility points are sufficient, so folks can add any MIME type they care about
2. Create a blessed list of MIME types and include them by default. The blessed list will be only what we use in Templates

[muratg]

@shirhatti I'm assuming you'll move this to 3.0?

[shirhatti]

Spent some time re-visiting compression. As mentioned in triage, the extensibility points we are sufficient.
We will not be adding any new MIME types by default that aren't assets shipped by the templates.