Epic: Create `golem-core` usage examples to verify its design

[approxit]

As first work item to start working with golem-core we decided to made some examples with it by whole team.

Todo:

• [x] Propose example topics to create
  • Examples could use different levels of abstraction (low/mid/high)
• [ ] Collect reviews about golem-core usability, its architecture, or ideas about possible upgrades

### Examples
- [ ] #62
- [ ] #61
- [ ] #63
- [ ] #64

[lucekdudek]

Examples

Geo location example

Discover provider's geo-location

CLI interactive walkthrough

Showcase what steps have to be complete in order to run simple task on golem - teaches how golem works

Profiling example

Example that profile providers, partially taken from yapapi examples:

• Take parts of blender example
• Run render of the same frame on multiple providers
• Check times that took provider to render single frame
• Outputs list of profiled providers, preferably sorted
• Flow of the example:
  • Create a demand
  • Listen to proposals until example exit
  • Run frame render on each arrived proposal
  • Display stats of provider render
  • Display summary of providers at example exit

Score based provider selection example

• Have input with a list of providers with rating (mapping of provider:score)
• Create a demand and wait for specific time, select n best providers (top in score)

Questions

• Is there any timeout from provider's proposal to accept that proposal?