AuthConstants updated to store separate constants when values diverge
between Coacheller and Lollapaloozer, i.e. COACH_GOOGLE_MOBILE_CLIENT_ID
vs LOLLA_GOOGLE_MOBILE_CLIENT_ID.  Only one file needs to be edited when
these external application constants change.

CoachellerApplication and LollapaloozerApplication populate a
HashMap<String, String> with properties that are unique to this version of
the application.  For example, CoachellerApplication populates value of
COACH_GOOGLE_MOBILE_CLIENT_ID referenced by key string
ÎéÎíGOOGLE_MOBILE_CLIENT_IDÎéÎí and LollapaloozerApplication populates
value of LOLLA_GOOGLE_MOBILE_CLIENT_ID referenced by the same key string
ÎéÎíGOOGLE_MOBILE_CLIENT_IDÎéÎí

AuthModel code is shared between applications, constructor now accepts a
HashMap<String, String> with properties unique to this version of the
application.  The Model storing this data seems appropriate for MVC
pattern implementation.

When parts of the application wish to access an application-specific
constant, instead of AuthConstants.LOLLA_GOOGLE_MOBILE_CLIENT_SECRET they
call _authModel.getAppConstant(AuthConstants.GOOGLE_MOBILE_CLIENT_SECRET)

This new code makes no specific reference to either Coacheller or
Lollapaloozer and so it can be executed by either application.
Merge branch 'master' of https://github.com/amyfan/Coacheller