Fix for MTOMCAT-177 - tomcat7:deploy ignores proxy settings

AbstractCatalinaMojo provides TomcatManager with proxy configuration from settings.xml

Note - I've added a MavenSession component to AbstractCatalinaMojo - it would probably be possible to use wagonManager.getProxy(url.getProtocol()) as done here: 

https://code.google.com/p/maven-external-dependency-plugin/issues/detail?id=15 

...I'm not sure if that would be best practice, but it seems to be deprecated: 

http://maven.apache.org/ref/3.0.5/maven-compat/apidocs/org/apache/maven/artifact/manager/WagonManager.html
However, maven config documentation states:

```
<!-- proxies
 | This is a list of proxies which can be used on this machine to connect to the network.
 | Unless otherwise specified (by system property or command-line switch), the first proxy
 | specification in this list marked as active will be used.
 |-->
```
So, this is actually maven compliant. I just need change the order of proxies, or specify one via command line. :+1: