[TASK] Improve validation mixin

[TASK] Ignore validation for non-required empty/undefined/null attributes

[FIX] Fail isNumber validation if value is NaN

[TASK] Create separate validation method for single attribute/value
[FIX] Use correct database column name for memos
[TASK] Validate using dispatcher and mixin
[TASK] Code cleanup
[TASK] Create glyphicon chevron shared module to toggle between up/down icons
[TASK] Remove highlighting of new payments in preparation of pagination