Added missing required newline at end of some `.gitignore` files. All other `.gitignore` files ends with a newline except the changed ones, hence the PR.
> *List which issues are fixed by this PR. You must list at least one issue. An issue is not required if the PR fixes something trivial like a typo.*
**Not listing any issues because of trivial fixes as mentioned above.**
Plugin projects are created by running `flutter create --plugin <name>`.
An example app is also created in the plugin project, using the normal 'create' template, which has been modified to allow for conditional plugin code.
Modified the android package name to match package naming conventions (all lower-case, and must match the directory name).
