Code refactoring

[leonidboykov]

Many parts have been rewritten from scratch.

• Better API handing with sling package
• Better API for predefined boards and sources
• New providers (in progress)

[todo]

Add `version` command.

getmoe/cmd/getmoe/version.go

Line 9 in 6d9df67

// TODO: Add `version` command.

---

This comment was generated by todo based on a TODO comment in 6d9df67 in #36. cc @leonidboykov.

[todo]

Add `version` command.

getmoe/cmd/getmoe/version.go

Line 9 in 2aa98d5

// TODO: Add `version` command.

---

This comment was generated by todo based on a TODO comment in 2aa98d5 in #36. cc @leonidboykov.

[todo]

Remove it

getmoe/cmd/getmoe/downloader/downloader.go

Lines 157 to 162 in e949a7b

	// TODO: Remove it
	if float32(post.Width)/float32(post.Height) < 1.10 {
	continue
	}
	filteredPosts = append(filteredPosts, post)
	}

---

This comment was generated by todo based on a TODO comment in e949a7b in #36. cc @leonidboykov.