Remove .rollupcache folder from npm package

**I'm submitting a bug report**

* **Library Version:**
1.3.3

**Please tell us about your environment:**
* **Operating System:**
Windows 10

* **Node Version:**
8.12.0

* **NPM Version:**
6.4.1

* **JSPM OR Webpack AND Version**
webpack 4.29.6

* **Browser:**
all

* **Language:**
TypeScript 3.2.2

**Current behavior:**

The npm package contains a folder named .rollupcache, with subfolders and files. This causes on Windows a windows maximum path length exceeded when deleting.

See https://registry.npmjs.org/aurelia-validation/-/aurelia-validation-1.3.3.tgz

**Expected/desired behavior:**

Don't include the .rollupcache folder. It was not included in 1.3.1 version and previous ones.

See https://registry.npmjs.org/aurelia-validation/-/aurelia-validation-1.3.1.tgz

Also occurs in aurelia-dialog (https://github.com/aurelia/dialog/issues/370).

* **What is the expected behavior?**

I expect to not have a windows maximum path length exceeded when deleting as in versions 1.3.1 and previous.

* **What is the motivation / use case for changing the behavior?**

The motivation is to not have a windows maximum path length exceeded when deleting as in versions 1.3.1 and previous and reduce package size.

Start by inspecting the package and publish configuration that determines which files enter the npm tarball, then compare the 1.3.3 and 1.3.1 package contents using the linked registry archives. Done means the .rollupcache folder is absent from the published package and the package can be deleted on Windows without exceeding the maximum path length.

Written by the indexing model from the issue text.