Add ISSUE_TEMPLATE to repository

[silkentrance]

Current reports lack viable information such as the operating system / version, the tmp version and the node js version.

I'd suggest that we add a proper template to the repository so that users can simply fill out the form.

cf. https://github.com/blog/2111-issue-and-pull-request-templates

@raszi What do you think?

Issue Template Proposal

Operating System

• Linux
• Windows 7
• Windows 10
• MacOS
• other:

NodeJS Version

• 0.x
• 4.x
• 6.x
• 7.x
• other:

Tmp Version

TBD:Enter tmp version here

Expected Behavior

TBD:What have you expected tmp to do?

Experienced Behavior

TBD:What did actually happen?

The template

## Operating System
- [ ] Linux
- [ ] Windows 7
- [ ] Windows 10
- [ ] MacOS
- other: 

## NodeJS Version
- [ ] 0.x
- [ ] 4.x
- [ ] 6.x
- [ ] 7.x
- other: 

## Tmp Version
TBD:Enter tmp version here

## Expected Behavior
TBD:What have you expected tmp to do?

## Experienced Behavior
TBD:What did actually happen?

[raszi]

This looks good. Could you add it please? Thank you!