Make requests intervals configurables for Home and Foreign

[patitonar]

Right now intervals to get information related to the network as current block number, events, limits and balance are fixed values for Home and Foreign. It makes sense to make those intervals configurable, so we should introduce:

• An environmental variable for Home interval

• An environmental variable for Foreign interval

[akolotov]

Let's consider different intervals for different set of information.
For example, the number of authorities and number of required signatures is not going to be changed often. So, it could be updated once in few minutes (and we can provided the info "this values are updated once in ... minutes" if it make sense).