(chore) prepare for 3.0 (optimizely#265)

* prepare for 3.0

* fix date

* add bug fixes and formatting to change log

* add indent

* nikhal feedback

* add link to pr for bug fix

(chore):Fix2.1.5 (optimizely#245)

* have the buffer reader call wrapped in a try catch in case of exception (optimizely#241)

* update changelog for patch release (optimizely#244)

update for latest RC (optimizely#238)

Refact: Copying attributes into new copiedAttributes variable (optimi…

…zely#227)

* Refact: Copying attributes into new copiedAttributes variable

* changed description of copyAttribute function

chore: release 2.1.1 (optimizely#195)

* Fix impression sent from feature experiment variation toggled off. (optimizely#193)

chore: release 2.0.2 (optimizely#194)

* Fix impression sent from feature experiment variation toggled off. (optimizely#193)

Update date (optimizely#190)