Add the call_next_at column, and REGEX matching
Add the call_next_at column, and REGEX matching

- To ensure that the format of the column value doesn't get corrupted
- Validation is done at client side, using JS, Regex.

Related issue: #47

icyflame/erp-rails,icyflame/erp-rails,aniarya82/networking-rails,icyflame/erp-rails,aniarya82/networking-rails,aniarya82/networking-rails