ENSession: cache the businessUser object, and refresh the notebook list on launch

Change-Id: I39b82f9115b6b08bb16e3a53dd62d5271b204d41
ENSession: add listWritableNotebooksWithCompletion to list writable notebooks with completion handler

Change-Id: I1fb61d77a68a2a74ea90a85db60b77065f777ad3
fix code sample
Sample App: listing tags (personal and business)

Change-Id: I2705e0c39fc4cf30c7bdf41a82662c85ab31b145
ENNoteStoreClient: when creating a new notebook, clean the local notebook list cache

This should fix https://github.com/evernote/evernote-cloud-sdk-ios/issues/19

Change-Id: Ia4a95c7f2f2ffe54a7f5870e47b914aa9469d517
ENSession: add upload usage property so the client can tell if a user is about to exceed the upload limit

Can be used to handle https://github.com/evernote/evernote-cloud-sdk-ios/issues/52

Change-Id: I64c05201cf0cb2556d88da1f6f2f0d4cf6c67187
ENSaveToEvernoteActivity: change to action category so it will be in the bottom row of the share sheet

Change-Id: I883734016907208742da09c8ead9071d57d11b3f
ENSaveToEvernoteActivity: if an UIActivityItem is an ENNote, just use the item as the prepared note

Change-Id: I6526ac42db9d916f4694ce05af88cfd9d1e6c610
ENSaveToEvernoteActivity: fix handling ENNote as one of the activity items

Change-Id: Ibd6e46df7adda9949645fca92dbcad63c9344712
ENSession: add boolean flag to let clients opt out from refreshing the notebooks cache on launch

fix https://github.com/evernote/evernote-cloud-sdk-ios/issues/54

Change-Id: I715e49c0a386f7a10eca79694bf6a064d3a3a28e
Readme: remove the outdated FAQ question.

Change-Id: I7a58dd99324d985948f1284a811806931fa0b6cf
Getting Started: fix the instruction of adding the framework and the resource bundle

Change-Id: I66534e8b80aea252a524bb39bff54edf72fe186c
Support PDF display
Improve PDF display support
fix css button color