Fixes the build deps between opentxs and opentxs-server.

Adds a COMPONENT name. Otherwise the build package would be called
opentxs-*-Unspecified. In the opentxs-server package a dependency is
defined on the opentxs package. There was no such package. This commit
lets opentxs-server reference opentxs-main (it had to have a suffix).
Merge pull request #173 from haarts/fix_ubuntu_package_deps

Fixes the build deps between opentxs and opentxs-server.