You should create a test environment locally with v1.7.0 and test the plugins with it.
When Installing latest NodeBB (0.8.2) it installs an incompatible version of nodebb-plugin-emailer-mandrill
I just did an install of NodeBB 0.8.2 and it installed nodebb-plugin-emailer-mandrill 0.3.1 with it which is only compatible with NodeBB 0.9.^. In addition to the declared version problem I was also getting a socket.io/helpers related error on NodeBB startup until I removed the mandrill plugin.
I worked around this problem by removing mandrill and then installing it like this:
npm install email@example.com
I poked around to see how nodebb installs nodebb-plugin-emailer-mandrill and it appears that this plugin is installed in a special way? It is not mentioned in the package.json requirements for nodebb.