Update apollo-client in / from 2.0.3 to 2.4.0

[dependencies]

Dependencies.io has updated apollo-client (a npm dependency in /) from "2.0.3" to "2.4.0".

2.4.0

• Add proper error handling for subscriptions. If you have defined an error
  handler on your subscription observer, it will now be called when an error
  comes back in a result, and the next handler will be skipped (similar to
  how we're handling errors with mutations). Previously, the error was
  just passed in the result to the next handler. If you don't have an
  error handler defined, the previous functionality is maintained, meaning
  the error is passed in the result, giving the next handler a chance to deal
  with it. This should help address backwards compatibility (and is the reason
  for the minor version bumo in this release).
  
  clayne11 in #3800
• Allow an optimistic param to be passed into ApolloClient.readQuery and
  ApolloClient.readFragment, that when set to true, will allow
  optimistic results to be returned. Is false by default.
  
  jay1337 in #2429
• Optimistic tests cleanup.
  
  joshribakoff in #3713
• Make sure each package has its own .npmignore, so they're taken into
  consideration when publishing via lerna.
  
  hwillson in #3828
• Documentation updates.
  
  toolness in #3804
  
  pungggi in #3798
  
  lorensr in #3748
  
  joshribakoff in #3730
  
  yalamber in #3819
  
  pschreibs85 in #3812
  
  msreekm in #3808
  
  kamaltmo in #3806
  
  lorensr in #3739
  
  brainkim in #3680

Apollo Cache In-Memory (1.2.8)

• Fix typo in console.warn regarding fragment matching error message.
  
  combizs in #3701

Apollo Boost (0.1.14)

• No changes.

Apollo Cache (1.1.15)

• No changes.

Apollo Utilities (1.0.19)

• No changes.

Apollo GraphQL Anywhere (4.1.17)

• No changes.