Added support for multiple source locations, and using the Maven FileSet parameter

**Add multiple resource locations and destinations**
Use the following Maven XML to add multiple sources and destinations to the update-stylesheets, and watch goal. This way it is possible to have multiple directories (with different path) in a project that produce css.
This is especially useful when the watch goal uses different settings then the update-stylesheets goal.

 ```xml
<resources>
	<resource>
		<source>
			<directory>${basedir}/src/main/resources/css</directory>
			<includes>
				<include>**</include>
			</includes>
			<excludes>
				<exclude>**/css-settings</exclude>
			</excludes>
		</source>
		<destination>${htdocsLocation}/css</destination>
	</resource>
	<resource>
		<source>
			<directory>${basedir}/src/main/resources/sass</directory>
			<includes>
				<include>**/css-settings-watch</include>
			</includes>
		</source>
		<destination>${htdocsLocation}/css</destination>
	</resource>
</resources>
 ```

**Watch goal**
The watch goal doesn't work in this plugin, because the SASS lib contains the Listen Gem, that has a reference to "__FILE__" which won't work when the file is in a jar package. Temporary solution:

Change / vendor / listen / lib / listen / directory_record.rb
```ruby
HIGH_PRECISION_SUPPORTED = File.mtime(__FILE__).to_f.to_s[-2..-1] != '.0'
```
To
 ```ruby
begin
    HIGH_PRECISION_SUPPORTED = File.mtime(__FILE__).to_f.to_s[-2..-1] != '.0'
rescue
    HIGH_PRECISION_SUPPORTED = false
end
```