minor features, layout improvements, many fixes

minor features, layout improvements, many fixes

- updated gems, especially math_engine
- implemented new fields on SecurityBond: :date_issue, :date_first_call,
  :call_price, :call_interval, :call_notify_deadline
- implemented Fix-to-Float type on SecurityBond
- implemented trading ceased option on Security, make use of it
- implemented #yield_to_call on security type models
- accept rounding issues up to 0.01 during #settle cash positions
- clarified organization and security portraits
- changed Fixnum to Integer for ruby 2.4
- BUGFIX: solving Free Cashflow(2016-q1) failed
- BUGFIX: use other css selector for :fund Securities
- BUGFIX: quote update skipped because if last_quote check failure
- BUGFIX: properly identify cashpositions by timestamp
- BUGFIX: never checkin schema_migrations.yml (causes great havoc)
- BUGFIX: #update_quote is to survive raises by reapers as well
- BUGFIX: flatten! can return nil which triggers uniq! to fail
- BUGFIX: handle big prices such as 12.575,390 EUR
- BUGFIX: survive Quote.safe! exceptions, but log that
- BUGFIX: avoid exception on non-existing table elements