feature added - attribute-support for every merged svg object

+ added code in the task - mostly string concatenation of attributes, defined in options
+ added a test task in Gruntfile.js
+ added a test and an appropriate file to compare

message to @FWeinb: it started with a weird bug caused by writing viewBox the right way (v0.2.3). In v0.2.2 the svgs didnt scale - accidently and caused by writing 'viewbox' the lower-case-way. But for me, this behavior was the one I needed to (open/close animations).
After some research I found the reason [here](http://www.justinmccandless.com/blog/Making+Sense+of+SVG+viewBox%27s+Madness) and [here](https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/preserveAspectRatio). So I decided to solve my issue in a more generally way. maybe you wanna merge it into the original package.
Please don't fix the trailing comma. It makes it easer to add new properties. And is valid as per [spec](http://es5.github.io/#x11.1.5)