[FIX] Display issues on SHA coins

* [FIX] Estimated shares on various places
* [ADDED] Calculate estimated shares based on network diff in stats
  class
* [UPDATED] Themes updated as needed

Fixes #819 once merged
[FIX] Worker Hashrates in Account -> My Worker
Merge pull request #821 from TheSerapher/issue-819

[FIX] Display issues on SHA coins