Fire storage deal provider ready event after startup completes

[dirkmc]

Ensure that the "ready" event is only fired after the start() method returns

[codecov-commenter]

Codecov Report

Merging #708 (a9652b0) into master (70dbd2f) will increase coverage by 0.08%.
The diff coverage is 49.13%.

@@            Coverage Diff             @@
##           master     #708      +/-   ##
==========================================
+ Coverage   58.60%   58.67%   +0.08%     
==========================================
  Files          64       64              
  Lines        5362     5398      +36     
==========================================
+ Hits         3142     3167      +25     
- Misses       1882     1886       +4     
- Partials      338      345       +7     

Impacted Files	Coverage Δ
storagemarket/impl/client.go	21.38% <ø> (ø)
storagemarket/impl/provider_environments.go	9.35% <0.00%> (+0.18%)	⬆️
storagemarket/impl/providerutils/providerutils.go	94.29% <ø> (ø)
storagemarket/types.go	85.37% <ø> (ø)
...oragemarket/impl/providerstates/provider_states.go	84.35% <33.34%> (-0.63%)	⬇️
storagemarket/impl/provider.go	26.63% <52.39%> (+3.74%)	⬆️
storagemarket/impl/clientutils/clientutils.go	40.55% <55.56%> (+1.84%)	⬆️