Remove dead code

[Neopallium]

Remove some old dead code and unneeded Substrate deps.

Also removed pallet_rewards.

[codecov[bot]]

Codecov Report

Merging #1509 (93b5ff7) into develop (fb7e530) will increase coverage by 3.53%. The diff coverage is 25.00%.

:exclamation: Current head 93b5ff7 differs from pull request most recent head e39f2db. Consider uploading reports for the commit e39f2db to get more accurate results

@@             Coverage Diff             @@
##           develop    #1509      +/-   ##
===========================================
+ Coverage    53.97%   57.51%   +3.53%     
===========================================
  Files          145      141       -4     
  Lines        32501    30497    -2004     
===========================================
- Hits         17541    17539       -2     
+ Misses       14960    12958    -2002     

Files Changed	Coverage Δ
pallets/common/src/context.rs	22.59% <0.00%> (+3.96%)	:arrow_up:
pallets/common/src/lib.rs	68.85% <ø> (+0.10%)	:arrow_up:
pallets/runtime/common/src/runtime.rs	1.81% <ø> (ø)
pallets/runtime/develop/src/runtime.rs	3.65% <0.00%> (ø)
pallets/weights/src/lib.rs	57.40% <ø> (ø)
pallets/identity/src/lib.rs	22.05% <100.00%> (ø)

... and 13 files with indirect coverage changes