add a lint check for Math.random

[trevj]

I can't find one out of the box but it may not be hard to build. Important to ensure we don't accidentally introduce further calls to it.

[jab]

Some initial progress in d415197

$ grunt build                                                                                                                                                                                              Running "exec:rmIosBuild" (exec) task

Running "exec:rmAndroidBuild" (exec) task

Running "tslint:files" (tslint) task
>> src/generic_core/local-instance.ts[64, 26]: function invocation disallowed: Math.random
>> src/generic_core/local-instance.ts[122, 36]: function invocation disallowed: Math.random
>> src/generic_core/remote-connection.ts[33, 28]: function invocation disallowed: Math.random
>> src/generic_core/social.ts[545, 32]: function invocation disallowed: Math.random
>> src/generic_core/social.ts[559, 18]: function invocation disallowed: Math.random
>> src/generic_ui/polymer/cloud-install.ts[66, 34]: function invocation disallowed: Math.random
>> src/generic_ui/scripts/ui.ts[366, 30]: function invocation disallowed: Math.random
>> src/lib/aqm/aqm.ts[101, 35]: function invocation disallowed: Math.random
>> src/lib/aqm/aqm.ts[107, 9]: function invocation disallowed: Math.random
>> src/mocks/freedom-mocks.ts[63, 29]: function invocation disallowed: Math.random
>> 10 errors in 219 files
Warning: Task "tslint:files" failed. Use --force to continue.

Aborted due to warnings.