[FIX] Show error msg when insufficient XRP to send

If the user does not have enough XRP and there are no alternative paths,
an informative error message is displayed.
[FIX] Send URI is defaulting to XRP (not the correct currency) (RT-2060)
[TASK] bump ripple-lib to 0.8.1
[TASK] Memo field: Add version to all transactions
[FIX] Clearer text than "offline" and "loading.."
[FIX] Path finding stopped working with gateway account (RT-2218, RT-2215)

* Specifying every currency/issuer pairs with positive amounts only while
  doing path-finding.
* Allow issue currency when the currency has both positive and negative
  components.
* Fix path displayed as n/a.
  (related to "Selected currency should be the first option")
* Fix a bug when exchanging currencies without full names.
[FIX] Memo field: Use rootScope to get version number
Merge pull request #1518 from mrajvanshy/clearerLoading

[FIX] Clearer text than "offline" and "loading.."
Merge pull request #1515 from yongsoo/feature/memo

[TASK] Memo field: Add version to all transactions
Merge pull request #1511 from geertweening/develop

[TASK] bump ripple-lib to 0.8.1
[FIX] Display Ripple names on the overview page
[FIX] Migrate: update text
Merge pull request #1514 from orzFly/fix/rt-2218

[FIX] Path finding stopped working with gateway account (RT-2218, RT-2215)
Merge pull request #1487 from bss-/send-xrp-insufficient-error

[FIX] Show error msg when insufficient XRP to send
Merge pull request #1505 from orzFly/fix/uri/send-currency

[FIX] Send URI is defaulting to XRP (not the correct currency) (RT-2060)
Merge pull request #1523 from mrajvanshy/rippleNamesOverview

[FIX] Display Ripple names on the overview page
Merge pull request #1524 from annatonger/fix/migrationtext

[FIX] Migrate: small text changes to make migrating more clear:
Merge branch 'develop' of github.com:ripple/ripple-client into develop