1.0 and 2.0 milestones

[ishkawa]

There are 2 issues that are pinned at 1.0 milestone, but I would like to release current master as 1.0 for the following reasons:

• Result 0.6.0-beta.6 is stable enough. IMO, we can specify the version by ~> 0.6.0. Upgrade Result to 1.0 #89
• Task interceptor mechanism needs further consideration. Additionally, I would like to avoid making large change in this version. [WIP] Add mechanism to intercept requests #87

After releasing 1.0.0, I'm planning to work on following topics:

• Better error handling model (turns returning custom error easy)
• Task interceptor
• Protocol-based request body builder and response body parser
• Request body builder for multipart/form-data

These changes may be breaking, but scale of changes is smaller than that of 0.x -> 1.0.
I'm confident that they improve library interface significantly 😉

[ishkawa]

1.0.0 is released 🎉
Task interceptor and multipart/form-data will be contained in 1.2.0 milestone.
The others will be considered in the next January (I got holidays through a month!).