Add deprecation warnings for bounded/unbounded assumptions

In [1]: x.is_bounded
./bin/isympy:1: SymPyDeprecationWarning:

is_bounded has been deprecated since SymPy 0.7.6. Use is_finite
instead. See https://github.com/sympy/sympy/issues/7943 for more info.

  #!/usr/bin/env python

In [2]: b = Symbol('b', bounded=True)
/home/sk/src/sympy/sympy/sympy/core/symbol.py:80: SymPyDeprecationWarning:

bounded assumption has been deprecated since SymPy 0.7.6. Use finite
instead. See https://github.com/sympy/sympy/issues/7943 for more info.

  if new_key:

In [3]: b.assumptions0
Out[3]: {'commutative': True, 'finite': True, 'infinite': False}

In [4]: