Making all plugins optional.

[kevgliss]

This PR makes all plugins optional. With this change, no plugin configuration will be necessary to create a new incident.

Additionally, the PR makes us much more resilient to some types of failures by remove message dependencies by ensuring that if no data is presented to a message that item is simply not rendered (as opposed to throwing an error).

[lgtm-com]

This pull request introduces 10 alerts and fixes 1 when merging 73c5aa2 into 5a80baa - view on LGTM.com

new alerts:

• 10 for Wrong number of arguments in a call

fixed alerts:

• 1 for Unused import

[lgtm-com]

This pull request introduces 10 alerts and fixes 1 when merging 6ecf8cf into 5a80baa - view on LGTM.com

new alerts:

• 10 for Wrong number of arguments in a call

fixed alerts:

• 1 for Unused import

[lgtm-com]

This pull request fixes 1 alert when merging 51ed1bd into 2fe6b90 - view on LGTM.com

fixed alerts:

• 1 for Unused import

[lgtm-com]

This pull request introduces 4 alerts and fixes 1 when merging 2545f78 into c4b5224 - view on LGTM.com

new alerts:

• 4 for Unused import

fixed alerts:

• 1 for Unused import

[lgtm-com]

This pull request fixes 1 alert when merging 457d973 into 6324e62 - view on LGTM.com

fixed alerts:

• 1 for Unused import

[lgtm-com]

This pull request fixes 1 alert when merging 4f3753d into 0825483 - view on LGTM.com

fixed alerts:

• 1 for Unused import

[lgtm-com]

This pull request fixes 1 alert when merging a3f4b03 into 0825483 - view on LGTM.com

fixed alerts:

• 1 for Unused import

[lgtm-com]

This pull request fixes 2 alerts when merging 27ddea4 into 0825483 - view on LGTM.com

fixed alerts:

• 2 for Unused import

[lgtm-com]

This pull request fixes 2 alerts when merging 487a6aa into 4f5da6b - view on LGTM.com

fixed alerts:

• 2 for Unused import