ionic change application package name

Go to config.xml and change the value of id attribute like:

<widget id="com.bospp.softwarecostestimation" version="0.0.1" xmlns="http://www.w3.org/ns/widgets" xmlns:cdv="http://cordova.apache.org/ns/1.0">
  <name>SoftwareCostEstimation</name>
  <description>
        An Software Cost Estimation App
    </description>
  <author email="rahul@bospp.com" href="http://bospp.com/">
      Rahul Jain
    </author>

...
...
...

</widget>

After changing values you have to run ionic build android command.

Also you can change other values like email, author etc.