Add modified_date to list of activity tokens

[mattwire]

Overview

For some reason modified_date was not included in the list of activity tokens. It works perfectly when added. This is especially useful for sending out emails with text such as "XX was modified at XX".

Before

We have activity_date_time and created_date but not modified date for tokens.

After

All 3 date fields available for activity tokens.

Technical Details

Comments

[civibot]

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[yashodha]

@mattwire
looks good, can be merged.

[seamuslee001]

Merging as per review from @yashodha