Parity Ethereum 2.1.7-stable

Parity-Ethereum 2.1.7-stable is a release that improves performance and stability.

System	Architecture	Binary	SHA256 Checksum
	x64	parity.exe	9a3fcd2366ba8873587f61ab5dd8b1d0fdb97c0286db488ad15c8543c19fa51c
	x64	parity	74379e83315175ce4c24d2901d025d5ec72927f1e27408dbc4f390ab815fc8a5
	x64	parity	2650354613a26cb501d5379dfb4449e4673eeed90e908759353464af1450eff0
System	Option	-	Resource
	Homebrew	-	github.com/paritytech/homebrew-paritytech
	Docker	-	hub.docker.com/r/parity/parity
	All binaries	-	vanity-service.parity.io/parity-binaries?version=v2.1.7

The full list of included changes:

• Backports for stable 2.1.7 (#9975)
  • Version: bump stable to 2.1.7
  • Adjust requests costs for light client (#9925)
    • Pip Table Cost relative to average peers instead of max peers
    • Add tracing in PIP new_cost_table
    • Update stat peer_count
    • Use number of leeching peers for Light serve costs
    • Fix test::light_params_load_share_depends_on_max_peers (wrong type)
    • Remove (now) useless test
    • Remove load_share from LightParams.Config
    • Add LEECHER_COUNT_FACTOR
    • Pr Grumble: u64 to u32 for f64 casting
    • Prevent u32 overflow for avg_peer_count
    • Add tests for LightSync::Statistics
  • Fix empty steps (#9939)
    • Don't send empty step twice or empty step then block.
    • Perform basic validation of locally sealed blocks.
    • Don't include empty step twice.
  • Prevent silent errors in daemon mode, closes #9367 (#9946)
  • Fix light client informant while syncing (#9932)
    • Add is_idle to LightSync to check importing status
    • Use SyncStateWrapper to make sure is_idle gets updates
    • Update is_major_import to use verified queue size as well
    • Add comment for is_idle
    • Add Debug to SyncStateWrapper
    • fn get -> fn into_inner
  • Ci: rearrange pipeline by logic (#9970)
  • Ci: rearrange pipeline by logic
  • Ci: rename docs script
  • Add readiness check for docker container (#9804)
    • Update Dockerfile
    • Add sync check script
  • Fix docker script (#9854)
  • Dockerfile: change source path of the newly added check_sync.sh (#9869)
  • Do not use the home directory as the working dir in docker (#9834)
    • Do not create a home directory.
    • Re-add -m flag
  • Fix docker build (#9971)
  • Bump smallvec to 0.6 in ethcore-light, ethstore and whisper (#9588)
    • Bump smallvec to 0.6 in ethcore-light, ethstore and whisper
    • Bump transaction-pool
    • Fix test.
  • Patch cargo to use tokio-proto from git repo
  • Use patched version of untrusted 0.5.1
  • Ci: allow audit to fail