Support multiple templates

[stefanbschneider]

While supported in v1.0, passing and placing templates of multiple services is currently not supported in the latest, refactored version of B-JointSP.
The placement algorithm still supports multiple templates, so it's mostly about passing and reading multiple templates.

For that, the following needs to be done:

• Adjust the --template, -t CLI arg so that it can be listed multiple times to pass multiple templates, eg,: bjointsp -t template1 -t template2 .... For that, use action=append.
• Adjust place() to take and handle a list of templates rather than a single one
• Particularly, call read_template for each template. Afterwards, adapt the templates on the fly to allow sharing common components by calling adapt_for_reuse
• Test if passing, reading, and handling multiple templates works. Both with separate and shared components. Add an example command with multiple templates to Travis to ensure it runs without errors.