Cleanup legacy code

- Cleanup code in "src/runtime/runtime-activity.coffee",
  "src/slugify.coffee" and "src/author/slope_tool_sequence.coffee" for
  whitespaces.

- Change build order in "Cakefile.coffee".
Add file "expressionParser.coffee"

- Add file "expressionParser.coffee" and "expressionParser.js" which
  contains function to parse the expression for linear equation.
Modify code to parse graph decorations

- Modify 'example-data/input/LineConstructionSequence.json' to shift
  graph decorations showGraphGrid, showToolTipCoords and showCrossHairs
  in "panes".

- Add code to parse graph decorations showGraphGrid, showToolTipCoords
  and showCrossHairs irrespective of any sequence type.
Add support for Linear Expression

- Add new class 'runtime/dataref.coffee' for the parsed the expression
  data.

- Add reference of dataref name in the graph pane in
  'runtime/step.coffee'.

- Add pointType, lineType and lineSnapDistance to
  'runtime/Datadef.coffee'.

- Change 'PredefinedGraphPane' in 'author/author-panes.coffee'
  for 'LinearEquation'.
Change case of datadefName in dataref

- Change case of 'datadefname' in dataref to 'datadefName'.
Add JSON for 'pick-a-point' with expression

- Add a sample input 'pick-a-point-on-a-line-sequence.json' file in
  'example-data/input/' and expanded JSON into
  'example-data/expected-output/' for linear function graphing.

- Update 'example-data/runtimeSchema.json'.
Add spec test for 'expressionParser.coffee'

- Add 'expression.spec.coffee' file to test functionality of
  'expressionParser'.
Add sinusoidal expression to 'expressionParser'

- Update 'expressionParse.coffee' to parse sinusoidal expressions.

- Modify 'author/author-panes.coffee', 'runtime/dataref.coffee' and
  'runtime/runtime-activity.coffee' to parse sinusoidal expressions.
Add condition in 'expressionParser'

- Add a condition to fetch slope for expression 'y = +x'.
Update spec test for 'expressionParser'

- Update 'expression.spec.coffee' to test functionality for sinusoidal
  expression.
Add JSON with sinusoidal expression

- Add a sample input 'pick-a-point-with-sinusoidal-expression.json'
  file in 'example-data/input/' and expanded JSON into
  'example-data/expected-output/' for sinusoidal function graphing.

- Update 'example-data/runtimeSchema.json'.

- Fix typo error in 'initialPrompt'.
Add composite expression in 'expressionParser'

- Add composite expression support in 'expressionParser'.
Add spec test for 'expressionParser.coffee'

- Add 'expression.spec.coffee' file to test functionality of
  'expressionParser' for composite expression.

- Add a sample input 'pick-a-point-with-composite-expression.json'
  file in 'example-data/input/' and expanded JSON into
  'example-data/expected-output/' for composite expression graphing.

- Update 'example-data/runtimeSchema.json'.
Update 'cakefile.coffee' for spec tests

- Add coffeelint for spec test files.

- Cleanup code in 'spec/convertor.spec.coffee' and
  'spec/schema.spec.coffee'.
Update JSON files

- Update JSON files.
Update JSON files

- Update JSON files.
Revert c85cb7ceafd1ac0678767e3a161bed043cfa2d34

- This reverts commit c85cb7ceafd1ac0678767e3a161bed043cfa2d34
  "Updated expected output for line-construction: rename page".

- Necessary changes have been done on the input file.
Merge pull request #2 from zeuslearning/zeus_rebase_9_12_12_a

Equations can be given in the semantic JSON instead of data-set for graphing.