add check price.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	ripple-examples/ripple-cli/src/main/java/com/ripple/cli/CheckPrice.java
Merge remote-tracking branch 'upstream/master'
fix Bouncy Castle lib can't not using on android.
Why?
The Android platform unfortunately ships with a cut-down version of
Bouncy Castle - as well as being crippled, it also makes installing an
updated version of the libraries difficult due to classloader conflict

Spongy Castle is the stock Bouncy Castle libraries with a couple of
small changes to make it work on Android:

all package names have been moved from org.bouncycastle.* to
org.ripple.bouncycastle.* - to avoid classloader conflicts
also refer to http://rtyley.github.io/spongycastle.
removed unused files.
add travis.yml ci file
for ci test
for ci test
Merge branch 'master' of
https://github.com/MadeInChina/ripple-lib-java.git

Conflicts:
	ripple-examples/ripple-android/src/main/java/com/ripple/android/activities/PayOneDrop.java
for ci test
Merge branch 'master' of github.com:MadeInChina/ripple-lib-java

Conflicts:
	ripple-core/src/main/java/com/ripple/core/types/hash/HASH.java